The shrinking woman

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The shrinking woman
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Hung-Yi Chu, MD
Pauling Chu, MD, PhD

A 45-year-old woman who has been undergoing hemodialysis for 20 years presents with diffuse bone pain, pruritic skin, muscle weakness, and disability. About 8 years ago, she was diagnosed with uremic hyperparathyroidism and underwent two parathyroidectomy procedures and eight sessions of percutaneous alcohol ablation of the parathyroid gland.

Figure 1. Severe kyphoscoliosis and barrel chest deformity on lateral view of chest.
On physical examination, she appears to have shrunk by 20 cm over the past 8 years, measured as the vertical height from head to foot, or by 13 cm of total body length when the curvature of the thoracic spine is taken into account. Radiography clearly shows severe deformity of the spine and limbs (Figure 1 and Figure 2).

Figure 2. Bowing deformity of the right arm (left) and the right leg (right).
Laboratory testing reveals a serum calcium concentration of 11.9 mg/dL (reference range 8.2–10.2), inorganic phosphorus 6.6 mg/dL (reference range 2.3–4.7), albumin 3.9 g/dL (reference range 3.5–5.0), and parathyroid hormone 1,747 pg/mL (reference range 10– 69).

A technetium-99m sestamibi radionuclide scan shows bilateral parathyroid hyperplasia with no ectopic parathyroid adenomas. Although a surgeon she consulted 1 month ago declined to perform another parathyroidectomy for technical reasons, another surgeon agreed to do it at this time. Parathyroidectomy was successfully performed, after which the parathyroid hormone level decreased drastically, to 85 pg/mL.

To our surprise, her total body length increased by 6 to 7 cm after surgery, with partial straightening of the back and legs noted about 4 to 5 weeks after surgery. Furthermore, she was able to walk a short distance just a few weeks after surgery. Unfortunately, she died from sepsis the next year.

SEVERE UREMIC HYPERPARATHYROIDISM: A CLINICAL DILEMMA

The clinical appearance of reduced body length and diffuse bony deformity leading to “shrinking” as a consequence of prolonged severe uremic hyperparathyroidism has only rarely been reported.1 However, it is not uncommon for surgeons to decide against parathyroidectomy because of concerns of extensive subcutaneous fibrosis and recurrent laryngeal nerve damage associated with previous operations. The result is that the patient’s uremic hyperparathyroidism goes untreated, increasing the risk of long-term complications, as in this patient.

TYPICAL RADIOGRAPHIC FEATURES

Figure 3. “Rugger-jersey” spine (arrows) on lateral view of the thoracic spine.
This patient had all the cardinal radiographic manifestations of uremic hyperparathyroidism—a “salt-and-pepper” appearance of the skull, which is a sign of trabecular bone resorption; “rugger-jersey” spine, or widespread osteosclerosis below the end plates of each vertebral body (thus giving the appearance of the stripes on a rugby jersey) (Figure 3); and twisted upper and lower limbs with scattered phalangeal subperiosteal erosions due to exaggerated bone resorption and vascular calcification. Although the gold standard for diagnosing uremic osteodystrophy remains bone biopsy, these characteristic radiographic manifestations of extensive bone resorption with simultaneous biomarkers referring to high bone turnover are usually diagnostic. In fact, they may predict the duration and severity of the disease.2,3

Why the body length increases after parathyroidectomy is not yet known, but plausible mechanisms are the effects of a recovery of muscle strength and the vigorous bony remineralization that strengthens weight-bearing bones after resolution of uremic hyperparathyroidism.

THE DANGERS OF DELAYED TREATMENT

Delaying parathyroidectomy may induce prolonged and severe uremic hyperparathyroidism, as in this patient. Nevertheless, despite the delay, surgery was able to partially ameliorate the symptoms of hyperparathyroidism and improve the extreme bone deformity. However, the patient’s informed consent, a detailed preoperative evaluation, and exclusion of ectopic parathyroid adenomas are imperative before surgical treatment.

References
  1. Horensten ML, Boner G, Rosenfeld JB. The shrinking man. A manifestation of severe renal osteodystrophy. JAMA 1980; 244:267–268.
  2. Jevtic V. Imaging of renal osteodystrophy. Eur J Radiol 2003; 46:85–95.
  3. Ferreira MA. Diagnosis of renal osteodystrophy: when and how to use biochemical markers and non-invasive methods; when bone biopsy is needed. Nephrol Dial Transplant 2000; 15(suppl 5):8–14.
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Division of Nephrology, Department of Internal Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan

Pauling Chu, MD, PhD
Division of Nephrology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Address: Pauling Chu, MD, PhD, Division of Nephrology, Department of Medicine, Tri-Service General Hospital, 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan; email: pchu@seed.net.tw

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Pauling Chu, MD, PhD
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Pauling Chu, MD, PhD
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Division of Nephrology, Department of Internal Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan

Pauling Chu, MD, PhD
Division of Nephrology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Address: Pauling Chu, MD, PhD, Division of Nephrology, Department of Medicine, Tri-Service General Hospital, 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan; email: pchu@seed.net.tw

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Division of Nephrology, Department of Internal Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan

Pauling Chu, MD, PhD
Division of Nephrology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Address: Pauling Chu, MD, PhD, Division of Nephrology, Department of Medicine, Tri-Service General Hospital, 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan; email: pchu@seed.net.tw

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A 45-year-old woman who has been undergoing hemodialysis for 20 years presents with diffuse bone pain, pruritic skin, muscle weakness, and disability. About 8 years ago, she was diagnosed with uremic hyperparathyroidism and underwent two parathyroidectomy procedures and eight sessions of percutaneous alcohol ablation of the parathyroid gland.

Figure 1. Severe kyphoscoliosis and barrel chest deformity on lateral view of chest.
On physical examination, she appears to have shrunk by 20 cm over the past 8 years, measured as the vertical height from head to foot, or by 13 cm of total body length when the curvature of the thoracic spine is taken into account. Radiography clearly shows severe deformity of the spine and limbs (Figure 1 and Figure 2).

Figure 2. Bowing deformity of the right arm (left) and the right leg (right).
Laboratory testing reveals a serum calcium concentration of 11.9 mg/dL (reference range 8.2–10.2), inorganic phosphorus 6.6 mg/dL (reference range 2.3–4.7), albumin 3.9 g/dL (reference range 3.5–5.0), and parathyroid hormone 1,747 pg/mL (reference range 10– 69).

A technetium-99m sestamibi radionuclide scan shows bilateral parathyroid hyperplasia with no ectopic parathyroid adenomas. Although a surgeon she consulted 1 month ago declined to perform another parathyroidectomy for technical reasons, another surgeon agreed to do it at this time. Parathyroidectomy was successfully performed, after which the parathyroid hormone level decreased drastically, to 85 pg/mL.

To our surprise, her total body length increased by 6 to 7 cm after surgery, with partial straightening of the back and legs noted about 4 to 5 weeks after surgery. Furthermore, she was able to walk a short distance just a few weeks after surgery. Unfortunately, she died from sepsis the next year.

SEVERE UREMIC HYPERPARATHYROIDISM: A CLINICAL DILEMMA

The clinical appearance of reduced body length and diffuse bony deformity leading to “shrinking” as a consequence of prolonged severe uremic hyperparathyroidism has only rarely been reported.1 However, it is not uncommon for surgeons to decide against parathyroidectomy because of concerns of extensive subcutaneous fibrosis and recurrent laryngeal nerve damage associated with previous operations. The result is that the patient’s uremic hyperparathyroidism goes untreated, increasing the risk of long-term complications, as in this patient.

TYPICAL RADIOGRAPHIC FEATURES

Figure 3. “Rugger-jersey” spine (arrows) on lateral view of the thoracic spine.
This patient had all the cardinal radiographic manifestations of uremic hyperparathyroidism—a “salt-and-pepper” appearance of the skull, which is a sign of trabecular bone resorption; “rugger-jersey” spine, or widespread osteosclerosis below the end plates of each vertebral body (thus giving the appearance of the stripes on a rugby jersey) (Figure 3); and twisted upper and lower limbs with scattered phalangeal subperiosteal erosions due to exaggerated bone resorption and vascular calcification. Although the gold standard for diagnosing uremic osteodystrophy remains bone biopsy, these characteristic radiographic manifestations of extensive bone resorption with simultaneous biomarkers referring to high bone turnover are usually diagnostic. In fact, they may predict the duration and severity of the disease.2,3

Why the body length increases after parathyroidectomy is not yet known, but plausible mechanisms are the effects of a recovery of muscle strength and the vigorous bony remineralization that strengthens weight-bearing bones after resolution of uremic hyperparathyroidism.

THE DANGERS OF DELAYED TREATMENT

Delaying parathyroidectomy may induce prolonged and severe uremic hyperparathyroidism, as in this patient. Nevertheless, despite the delay, surgery was able to partially ameliorate the symptoms of hyperparathyroidism and improve the extreme bone deformity. However, the patient’s informed consent, a detailed preoperative evaluation, and exclusion of ectopic parathyroid adenomas are imperative before surgical treatment.

A 45-year-old woman who has been undergoing hemodialysis for 20 years presents with diffuse bone pain, pruritic skin, muscle weakness, and disability. About 8 years ago, she was diagnosed with uremic hyperparathyroidism and underwent two parathyroidectomy procedures and eight sessions of percutaneous alcohol ablation of the parathyroid gland.

Figure 1. Severe kyphoscoliosis and barrel chest deformity on lateral view of chest.
On physical examination, she appears to have shrunk by 20 cm over the past 8 years, measured as the vertical height from head to foot, or by 13 cm of total body length when the curvature of the thoracic spine is taken into account. Radiography clearly shows severe deformity of the spine and limbs (Figure 1 and Figure 2).

Figure 2. Bowing deformity of the right arm (left) and the right leg (right).
Laboratory testing reveals a serum calcium concentration of 11.9 mg/dL (reference range 8.2–10.2), inorganic phosphorus 6.6 mg/dL (reference range 2.3–4.7), albumin 3.9 g/dL (reference range 3.5–5.0), and parathyroid hormone 1,747 pg/mL (reference range 10– 69).

A technetium-99m sestamibi radionuclide scan shows bilateral parathyroid hyperplasia with no ectopic parathyroid adenomas. Although a surgeon she consulted 1 month ago declined to perform another parathyroidectomy for technical reasons, another surgeon agreed to do it at this time. Parathyroidectomy was successfully performed, after which the parathyroid hormone level decreased drastically, to 85 pg/mL.

To our surprise, her total body length increased by 6 to 7 cm after surgery, with partial straightening of the back and legs noted about 4 to 5 weeks after surgery. Furthermore, she was able to walk a short distance just a few weeks after surgery. Unfortunately, she died from sepsis the next year.

SEVERE UREMIC HYPERPARATHYROIDISM: A CLINICAL DILEMMA

The clinical appearance of reduced body length and diffuse bony deformity leading to “shrinking” as a consequence of prolonged severe uremic hyperparathyroidism has only rarely been reported.1 However, it is not uncommon for surgeons to decide against parathyroidectomy because of concerns of extensive subcutaneous fibrosis and recurrent laryngeal nerve damage associated with previous operations. The result is that the patient’s uremic hyperparathyroidism goes untreated, increasing the risk of long-term complications, as in this patient.

TYPICAL RADIOGRAPHIC FEATURES

Figure 3. “Rugger-jersey” spine (arrows) on lateral view of the thoracic spine.
This patient had all the cardinal radiographic manifestations of uremic hyperparathyroidism—a “salt-and-pepper” appearance of the skull, which is a sign of trabecular bone resorption; “rugger-jersey” spine, or widespread osteosclerosis below the end plates of each vertebral body (thus giving the appearance of the stripes on a rugby jersey) (Figure 3); and twisted upper and lower limbs with scattered phalangeal subperiosteal erosions due to exaggerated bone resorption and vascular calcification. Although the gold standard for diagnosing uremic osteodystrophy remains bone biopsy, these characteristic radiographic manifestations of extensive bone resorption with simultaneous biomarkers referring to high bone turnover are usually diagnostic. In fact, they may predict the duration and severity of the disease.2,3

Why the body length increases after parathyroidectomy is not yet known, but plausible mechanisms are the effects of a recovery of muscle strength and the vigorous bony remineralization that strengthens weight-bearing bones after resolution of uremic hyperparathyroidism.

THE DANGERS OF DELAYED TREATMENT

Delaying parathyroidectomy may induce prolonged and severe uremic hyperparathyroidism, as in this patient. Nevertheless, despite the delay, surgery was able to partially ameliorate the symptoms of hyperparathyroidism and improve the extreme bone deformity. However, the patient’s informed consent, a detailed preoperative evaluation, and exclusion of ectopic parathyroid adenomas are imperative before surgical treatment.

References
  1. Horensten ML, Boner G, Rosenfeld JB. The shrinking man. A manifestation of severe renal osteodystrophy. JAMA 1980; 244:267–268.
  2. Jevtic V. Imaging of renal osteodystrophy. Eur J Radiol 2003; 46:85–95.
  3. Ferreira MA. Diagnosis of renal osteodystrophy: when and how to use biochemical markers and non-invasive methods; when bone biopsy is needed. Nephrol Dial Transplant 2000; 15(suppl 5):8–14.
References
  1. Horensten ML, Boner G, Rosenfeld JB. The shrinking man. A manifestation of severe renal osteodystrophy. JAMA 1980; 244:267–268.
  2. Jevtic V. Imaging of renal osteodystrophy. Eur J Radiol 2003; 46:85–95.
  3. Ferreira MA. Diagnosis of renal osteodystrophy: when and how to use biochemical markers and non-invasive methods; when bone biopsy is needed. Nephrol Dial Transplant 2000; 15(suppl 5):8–14.
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Cleveland Clinic Journal of Medicine - 77(9)
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Recurrent pyelonephritis as a sign of ‘sponge kidney’

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Article
Changed
Mon, 03/05/2018 - 14:59
Display Headline
Recurrent pyelonephritis as a sign of ‘sponge kidney’
Author(s)
Hung-Yi Chu, MD
Ming-Tso Yan, MD
Shih-Hua Lin, MD

Figure 1. Radiograph, kidney-ureter-bladder view, showing multiple radiopaque densities (arrowheads) within bilateral renal shadows.
A 39-year-old woman presented 1 month ago with left flank pain, chills, and spiking fever over the past day. She reported having an episode of acute pyelonephritis with similar manifestations 6 months previously.

Figure 2. Computed tomographic scan of the abdomen showing bilateral renal medullary nephrocalcinosis (arrowheads).
Blood tests showed a leukocyte count of 12.2 × 109/L (normal range 7.05–14.99 × 109/L) with predominant neutrophils, C-reactive protein 6.3 mg/dL (0.0–1.0 mg/dL), blood urea nitrogen 16 mg/dL (10–25 mg/dL), and serum creatinine 1.1 mg/dL (0.70–1.40 mg/dL). Radiographic study of the kidneys, ureters, and bladder showed multiple radiopaque densities in the calyces of both kidneys (Figure 1). Computed tomography of the abdomen without contrast revealed multiple punctuated calcifications aligned concentrically in the medulla of both kidneys (Figure 2). Blood and urine cultures were positive for Escherichia coli that was sensitive to ceftriaxone (Rocephin). This antibiotic was started, and her acute pyelonephritis and bacteremia resolved.

Figure 3. Intravenous urogram at 10 minutes demonstrating the bright brush-like or “paintbrush” pattern (arrowheads) of contrast collection along ectatic medullary collecting tubules uniformly directing the cupping of papillae.
Now, at a follow-up visit 1 month later, intravenous urography clearly shows unique linear and striated opacities and cupping of renal papillae, key features of medullary sponge kidney (Figure 3). Because medullary sponge kidney is strongly associated with kidney stones, potassium citrate is given to prevent medullary calculi formation.

KEY FEATURES

Medullary sponge kidney causes extensive cystic dilation of medullary collecting tubules.1 It is usually an incidental finding in patients undergoing intravenous urography as part of the evaluation for infection, hematuria, or kidney stones.

The classic urographic appearance is linear striations with small brushes or “bouquets of flowers,” which represent the collection of contrast material in small papillary cysts.

Medullary sponge kidney has long been considered a congenital disorder, but the genetic defect has not yet been identified, and the pathogenesis is not yet known. It has only rarely been reported in children.2

It is usually asymptomatic, but complications may occur, including nephrocalcinosis or lithiasis, urinary tract infection, renal tubular acidosis, and impaired urine concentrating ability.

RISK OF LITHIASIS

Gambaro et al3 estimated that medullary sponge kidney is found in up to 20% of patients with urolithiasis, and that more than 70% of patients with medullary sponge kidney develop stones.

Cystic dilation of medullary collecting tubules (an anatomic abnormality) inevitably causes urinary stasis. This, combined with hypercalciuria and reduced excretion of urinary citrate and magnesium (metabolic abnormalities), contributes to lithiasis.4 Lithiasis in medullary sponge kidney is a well-known cause of urinary tract infection, and it tends to facilitate infective stone formation after episodes of urinary tract infection.5

The unique anatomic derangement of medullary sponge kidney contributes to the recurrence of pyelonephritis, in addition to the conventional risk factors—frequent sexual intercourse, avoidance of voiding because it is inconvenient, incomplete bladder emptying, ureteropelvic junction obstruction, ectopic ureter, and impaired immunity.6

DIAGNOSIS AND TREATMENT

Intravenous urography is the gold standard for the diagnosis of medullary sponge kidney; computed tomography and ultrasonography are generally limited in their ability to clearly show the tubular ectasia.7

Treatment includes antibiotics for acute pyelonephritis and thiazide diuretics and potassium citrate to prevent stone formation and renal tubular acidosis. Due to its silent course, medullary sponge kidney should be considered not only as a cause of nephrocalcinosis and nephrolithiasis, but also as a distinct entity complicating recurrent pyelonephritis.

References
  1. Gambaro G, Feltrin GP, Lupo A, Bonfante L, D'Angelo A, Antonello A. Medullary sponge kidney (Lenarduzzi-Cacchi-Ricci disease): a Padua Medical School discovery in the 1930s. Kidney Int 2006; 69:663–670.
  2. Kasap B, Soylu A, Oren O, Turkmen M, Kavukcu S. Medullary sponge kidney associated with distal renal tubular acidosis in a 5-year-old girl. Eur J Pediatr 2006; 165:648–651.
  3. Gambaro G, Fabris A, Puliatta D, Lupo A. Lithiasis in cystic kidney disease and malformations of the urinary tract. Urol Res 2006; 34:102–107.
  4. O'Neill M, Breslau NA, Pak CY. Metabolic evaluation of nephrolithiasis in patients with medullary sponge kidney. JAMA 1981; 245:1233–1236.
  5. Miano R, Germani S, Vespasiani G. Stones and urinary tract infections. Urol Int 2007; 79(suppl 1):32–36.
  6. Scholes D, Hooton TM, Roberts PL, Gupta K, Stapleton AE, Stamm WE. Risk factors associated with acute pyelonephritis in healthy women. Ann Intern Med 2005; 142:20–27.
  7. Maw AM, Megibow AJ, Grasso M, Goldfarb DS. Diagnosis of medullary sponge kidney by computed tomographic urography. Am J Kidney Dis 2007; 50:146–150.
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Division of Nephrology, Department of Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan, ROC

Ming-Tso Yan, MD
Division of Nephrology, Department of Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan, ROC

Shih-Hua Lin, MD
Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC

Address: Shih-Hua Lin, MD, Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Number 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan; e-mail shihhualin@yahoo.com

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Author(s)
Hung-Yi Chu, MD
Ming-Tso Yan, MD
Shih-Hua Lin, MD
Author(s)
Hung-Yi Chu, MD
Ming-Tso Yan, MD
Shih-Hua Lin, MD
Author and Disclosure Information

Hung-Yi Chu, MD
Division of Nephrology, Department of Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan, ROC

Ming-Tso Yan, MD
Division of Nephrology, Department of Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan, ROC

Shih-Hua Lin, MD
Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC

Address: Shih-Hua Lin, MD, Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Number 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan; e-mail shihhualin@yahoo.com

Author and Disclosure Information

Hung-Yi Chu, MD
Division of Nephrology, Department of Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan, ROC

Ming-Tso Yan, MD
Division of Nephrology, Department of Medicine, Ren-Ai Branch of Taipei City Hospital, Taipei, Taiwan, ROC

Shih-Hua Lin, MD
Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC

Address: Shih-Hua Lin, MD, Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Number 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan; e-mail shihhualin@yahoo.com

Article PDF
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Figure 1. Radiograph, kidney-ureter-bladder view, showing multiple radiopaque densities (arrowheads) within bilateral renal shadows.
A 39-year-old woman presented 1 month ago with left flank pain, chills, and spiking fever over the past day. She reported having an episode of acute pyelonephritis with similar manifestations 6 months previously.

Figure 2. Computed tomographic scan of the abdomen showing bilateral renal medullary nephrocalcinosis (arrowheads).
Blood tests showed a leukocyte count of 12.2 × 109/L (normal range 7.05–14.99 × 109/L) with predominant neutrophils, C-reactive protein 6.3 mg/dL (0.0–1.0 mg/dL), blood urea nitrogen 16 mg/dL (10–25 mg/dL), and serum creatinine 1.1 mg/dL (0.70–1.40 mg/dL). Radiographic study of the kidneys, ureters, and bladder showed multiple radiopaque densities in the calyces of both kidneys (Figure 1). Computed tomography of the abdomen without contrast revealed multiple punctuated calcifications aligned concentrically in the medulla of both kidneys (Figure 2). Blood and urine cultures were positive for Escherichia coli that was sensitive to ceftriaxone (Rocephin). This antibiotic was started, and her acute pyelonephritis and bacteremia resolved.

Figure 3. Intravenous urogram at 10 minutes demonstrating the bright brush-like or “paintbrush” pattern (arrowheads) of contrast collection along ectatic medullary collecting tubules uniformly directing the cupping of papillae.
Now, at a follow-up visit 1 month later, intravenous urography clearly shows unique linear and striated opacities and cupping of renal papillae, key features of medullary sponge kidney (Figure 3). Because medullary sponge kidney is strongly associated with kidney stones, potassium citrate is given to prevent medullary calculi formation.

KEY FEATURES

Medullary sponge kidney causes extensive cystic dilation of medullary collecting tubules.1 It is usually an incidental finding in patients undergoing intravenous urography as part of the evaluation for infection, hematuria, or kidney stones.

The classic urographic appearance is linear striations with small brushes or “bouquets of flowers,” which represent the collection of contrast material in small papillary cysts.

Medullary sponge kidney has long been considered a congenital disorder, but the genetic defect has not yet been identified, and the pathogenesis is not yet known. It has only rarely been reported in children.2

It is usually asymptomatic, but complications may occur, including nephrocalcinosis or lithiasis, urinary tract infection, renal tubular acidosis, and impaired urine concentrating ability.

RISK OF LITHIASIS

Gambaro et al3 estimated that medullary sponge kidney is found in up to 20% of patients with urolithiasis, and that more than 70% of patients with medullary sponge kidney develop stones.

Cystic dilation of medullary collecting tubules (an anatomic abnormality) inevitably causes urinary stasis. This, combined with hypercalciuria and reduced excretion of urinary citrate and magnesium (metabolic abnormalities), contributes to lithiasis.4 Lithiasis in medullary sponge kidney is a well-known cause of urinary tract infection, and it tends to facilitate infective stone formation after episodes of urinary tract infection.5

The unique anatomic derangement of medullary sponge kidney contributes to the recurrence of pyelonephritis, in addition to the conventional risk factors—frequent sexual intercourse, avoidance of voiding because it is inconvenient, incomplete bladder emptying, ureteropelvic junction obstruction, ectopic ureter, and impaired immunity.6

DIAGNOSIS AND TREATMENT

Intravenous urography is the gold standard for the diagnosis of medullary sponge kidney; computed tomography and ultrasonography are generally limited in their ability to clearly show the tubular ectasia.7

Treatment includes antibiotics for acute pyelonephritis and thiazide diuretics and potassium citrate to prevent stone formation and renal tubular acidosis. Due to its silent course, medullary sponge kidney should be considered not only as a cause of nephrocalcinosis and nephrolithiasis, but also as a distinct entity complicating recurrent pyelonephritis.

Figure 1. Radiograph, kidney-ureter-bladder view, showing multiple radiopaque densities (arrowheads) within bilateral renal shadows.
A 39-year-old woman presented 1 month ago with left flank pain, chills, and spiking fever over the past day. She reported having an episode of acute pyelonephritis with similar manifestations 6 months previously.

Figure 2. Computed tomographic scan of the abdomen showing bilateral renal medullary nephrocalcinosis (arrowheads).
Blood tests showed a leukocyte count of 12.2 × 109/L (normal range 7.05–14.99 × 109/L) with predominant neutrophils, C-reactive protein 6.3 mg/dL (0.0–1.0 mg/dL), blood urea nitrogen 16 mg/dL (10–25 mg/dL), and serum creatinine 1.1 mg/dL (0.70–1.40 mg/dL). Radiographic study of the kidneys, ureters, and bladder showed multiple radiopaque densities in the calyces of both kidneys (Figure 1). Computed tomography of the abdomen without contrast revealed multiple punctuated calcifications aligned concentrically in the medulla of both kidneys (Figure 2). Blood and urine cultures were positive for Escherichia coli that was sensitive to ceftriaxone (Rocephin). This antibiotic was started, and her acute pyelonephritis and bacteremia resolved.

Figure 3. Intravenous urogram at 10 minutes demonstrating the bright brush-like or “paintbrush” pattern (arrowheads) of contrast collection along ectatic medullary collecting tubules uniformly directing the cupping of papillae.
Now, at a follow-up visit 1 month later, intravenous urography clearly shows unique linear and striated opacities and cupping of renal papillae, key features of medullary sponge kidney (Figure 3). Because medullary sponge kidney is strongly associated with kidney stones, potassium citrate is given to prevent medullary calculi formation.

KEY FEATURES

Medullary sponge kidney causes extensive cystic dilation of medullary collecting tubules.1 It is usually an incidental finding in patients undergoing intravenous urography as part of the evaluation for infection, hematuria, or kidney stones.

The classic urographic appearance is linear striations with small brushes or “bouquets of flowers,” which represent the collection of contrast material in small papillary cysts.

Medullary sponge kidney has long been considered a congenital disorder, but the genetic defect has not yet been identified, and the pathogenesis is not yet known. It has only rarely been reported in children.2

It is usually asymptomatic, but complications may occur, including nephrocalcinosis or lithiasis, urinary tract infection, renal tubular acidosis, and impaired urine concentrating ability.

RISK OF LITHIASIS

Gambaro et al3 estimated that medullary sponge kidney is found in up to 20% of patients with urolithiasis, and that more than 70% of patients with medullary sponge kidney develop stones.

Cystic dilation of medullary collecting tubules (an anatomic abnormality) inevitably causes urinary stasis. This, combined with hypercalciuria and reduced excretion of urinary citrate and magnesium (metabolic abnormalities), contributes to lithiasis.4 Lithiasis in medullary sponge kidney is a well-known cause of urinary tract infection, and it tends to facilitate infective stone formation after episodes of urinary tract infection.5

The unique anatomic derangement of medullary sponge kidney contributes to the recurrence of pyelonephritis, in addition to the conventional risk factors—frequent sexual intercourse, avoidance of voiding because it is inconvenient, incomplete bladder emptying, ureteropelvic junction obstruction, ectopic ureter, and impaired immunity.6

DIAGNOSIS AND TREATMENT

Intravenous urography is the gold standard for the diagnosis of medullary sponge kidney; computed tomography and ultrasonography are generally limited in their ability to clearly show the tubular ectasia.7

Treatment includes antibiotics for acute pyelonephritis and thiazide diuretics and potassium citrate to prevent stone formation and renal tubular acidosis. Due to its silent course, medullary sponge kidney should be considered not only as a cause of nephrocalcinosis and nephrolithiasis, but also as a distinct entity complicating recurrent pyelonephritis.

References
  1. Gambaro G, Feltrin GP, Lupo A, Bonfante L, D'Angelo A, Antonello A. Medullary sponge kidney (Lenarduzzi-Cacchi-Ricci disease): a Padua Medical School discovery in the 1930s. Kidney Int 2006; 69:663–670.
  2. Kasap B, Soylu A, Oren O, Turkmen M, Kavukcu S. Medullary sponge kidney associated with distal renal tubular acidosis in a 5-year-old girl. Eur J Pediatr 2006; 165:648–651.
  3. Gambaro G, Fabris A, Puliatta D, Lupo A. Lithiasis in cystic kidney disease and malformations of the urinary tract. Urol Res 2006; 34:102–107.
  4. O'Neill M, Breslau NA, Pak CY. Metabolic evaluation of nephrolithiasis in patients with medullary sponge kidney. JAMA 1981; 245:1233–1236.
  5. Miano R, Germani S, Vespasiani G. Stones and urinary tract infections. Urol Int 2007; 79(suppl 1):32–36.
  6. Scholes D, Hooton TM, Roberts PL, Gupta K, Stapleton AE, Stamm WE. Risk factors associated with acute pyelonephritis in healthy women. Ann Intern Med 2005; 142:20–27.
  7. Maw AM, Megibow AJ, Grasso M, Goldfarb DS. Diagnosis of medullary sponge kidney by computed tomographic urography. Am J Kidney Dis 2007; 50:146–150.
References
  1. Gambaro G, Feltrin GP, Lupo A, Bonfante L, D'Angelo A, Antonello A. Medullary sponge kidney (Lenarduzzi-Cacchi-Ricci disease): a Padua Medical School discovery in the 1930s. Kidney Int 2006; 69:663–670.
  2. Kasap B, Soylu A, Oren O, Turkmen M, Kavukcu S. Medullary sponge kidney associated with distal renal tubular acidosis in a 5-year-old girl. Eur J Pediatr 2006; 165:648–651.
  3. Gambaro G, Fabris A, Puliatta D, Lupo A. Lithiasis in cystic kidney disease and malformations of the urinary tract. Urol Res 2006; 34:102–107.
  4. O'Neill M, Breslau NA, Pak CY. Metabolic evaluation of nephrolithiasis in patients with medullary sponge kidney. JAMA 1981; 245:1233–1236.
  5. Miano R, Germani S, Vespasiani G. Stones and urinary tract infections. Urol Int 2007; 79(suppl 1):32–36.
  6. Scholes D, Hooton TM, Roberts PL, Gupta K, Stapleton AE, Stamm WE. Risk factors associated with acute pyelonephritis in healthy women. Ann Intern Med 2005; 142:20–27.
  7. Maw AM, Megibow AJ, Grasso M, Goldfarb DS. Diagnosis of medullary sponge kidney by computed tomographic urography. Am J Kidney Dis 2007; 50:146–150.
Issue
Cleveland Clinic Journal of Medicine - 76(8)
Issue
Cleveland Clinic Journal of Medicine - 76(8)
Page Number
479-480
Page Number
479-480
Publications
Cleveland Clinic Journal of Medicine
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Cleveland Clinic Journal of Medicine
Topics
Nephrology
Imaging
Article Type
Article
Display Headline
Recurrent pyelonephritis as a sign of ‘sponge kidney’
Display Headline
Recurrent pyelonephritis as a sign of ‘sponge kidney’
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