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Distal renal tubular acidosis in a boy with Proteus syndrome
nephrology image
http://www.kidney-international.org & 2013 International Society of Nephrology Kidney International (2013) 83, 1209–1210; doi:10.1038/ki.2012.473
Distal renal tubular acidosis in a boy with Proteus syndrome Prasad Narayan1, Rangaswamy Dharshan1, Gupta Amit1, Sharma Raj Kumar1, Bhadauria Dharmender1 and Kaul Anupama1 1
Department of Nephrology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
Correspondence: Narayan Prasad, Department of Nephrology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Rae Bareli Road, Lucknow 226014, India. E-mail: [email protected] or [email protected]
a
Figure 1 | A boy with Proteus syndrome showing asymmetrical overgrowth of lower limbs, mainly megadactyly of feet (black arrow), increased carrying angle at elbow, and subcutaneous periumbilical lipoma (white arrow and inset).
A 15-year-old boy born of a non-consanguineous marriage presented for evaluation of intermittent gross hematuria persistent since the past 4 months. He had progressive and asymmetrical overgrowth of lower limbs (right 100.5 cm4 left 96 cm), with megadactyly (Figure 1, black arrow) and dilated tortuous veins on feet, increased carrying angle at elbow, and Kidney International (2013) 83, 1209–1210
b
Figure 2 | Computerized tomography (axial section) of abdomen. Non-contrast computed tomography (CT) study (a) shows multiple calcifications (black arrow), and contrast study (b) in late arterial and early venous phase shows dilated and torturous renal vein with possible collateral formation (white arrow) and calcifications (black arrow).
normal fingers of upper limb since birth. He had periumbilical lipoma confirmed with fine-needle aspiration cytology (Figure 1, white arrow with inset), left undescended testis, sparse pubic hair, and pigmented nevi compatible with the diagnosis of Proteus syndrome (PS). Biochemical investigations showed the following results: serum creatinine, 0.8 mg/dl; 1209
nephrology image
calcium, 8.6 mg/dl; potassium, 3.5 mmol/l; uric acid, 5.4 mg/ dl; and normal intact parathyroid hormone and 25(OH) vitamin D levels. His urinary calcium, urate, and oxalate levels were normal. His urinary citrate level was toward the lower limit of normal. His 24-h urine protein was 664 mg, and 40–50 red blood cells (RBCs)/high power field with no RBC cast on urine microscopy were detected. His baseline urine pH was 7.15, serum HCO3 was 20.1 mmol/l, and serum pH was 7.31. Ammonium chloride loading test revealed a urine pH of 5.97, with serum HCO3 being 15.8 mmol/l at 3 h, consistent with distal renal tubular acidosis (dRTA). Urine anion gap was 26 mmol/l. Non-contrast computed tomography scan (Figure 2a) showed medullary calcific density consistent with nephrocalcinosis in the right kidney, and contrast study (Figure 2b) in early venous phase revealed bilateral dilated and tortuous renal veins with possible collateral formation (white arrow) and calcifications (black arrow).
1210
P Narayan et al.: Distal renal tubular acidosis
PS is a rare sporadic disorder of asymmetric overgrowth of body parts due to somatic mosaicism involving the AKT1 gene on 14q32.33, which has a key role in regulating cell survival, insulin signaling, angiogenesis, and tumor formation. It is characterized by vascular malformations of the capillary, venous, and lymphatic systems, as well as cerebriform connective tissue nevi, epidermal nevi, and dysregulated adipose tissue (lipoma). Less common features include cystic lung disease, ovarian/parotid adenomas, and craniofacial and genito-urinary abnormalities. Genitourinary abnormalities include undescended testis, renal asymmetry, renal failure, ureteric asymmetry, renal cysts, nephrogenic diabetes, hematuria, hydronephrosis, proteinuria, and hydroureter. The mechanism underlying dRTA in this patient is unknown, and further investigation of biochemical pathways in this area may confirm the association of PS and dRTA.
Kidney International (2013) 83, 1209–1210
http://www.kidney-international.org & 2013 International Society of Nephrology Kidney International (2013) 83, 1209–1210; doi:10.1038/ki.2012.473
Distal renal tubular acidosis in a boy with Proteus syndrome Prasad Narayan1, Rangaswamy Dharshan1, Gupta Amit1, Sharma Raj Kumar1, Bhadauria Dharmender1 and Kaul Anupama1 1
Department of Nephrology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
Correspondence: Narayan Prasad, Department of Nephrology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Rae Bareli Road, Lucknow 226014, India. E-mail: [email protected] or [email protected]
a
Figure 1 | A boy with Proteus syndrome showing asymmetrical overgrowth of lower limbs, mainly megadactyly of feet (black arrow), increased carrying angle at elbow, and subcutaneous periumbilical lipoma (white arrow and inset).
A 15-year-old boy born of a non-consanguineous marriage presented for evaluation of intermittent gross hematuria persistent since the past 4 months. He had progressive and asymmetrical overgrowth of lower limbs (right 100.5 cm4 left 96 cm), with megadactyly (Figure 1, black arrow) and dilated tortuous veins on feet, increased carrying angle at elbow, and Kidney International (2013) 83, 1209–1210
b
Figure 2 | Computerized tomography (axial section) of abdomen. Non-contrast computed tomography (CT) study (a) shows multiple calcifications (black arrow), and contrast study (b) in late arterial and early venous phase shows dilated and torturous renal vein with possible collateral formation (white arrow) and calcifications (black arrow).
normal fingers of upper limb since birth. He had periumbilical lipoma confirmed with fine-needle aspiration cytology (Figure 1, white arrow with inset), left undescended testis, sparse pubic hair, and pigmented nevi compatible with the diagnosis of Proteus syndrome (PS). Biochemical investigations showed the following results: serum creatinine, 0.8 mg/dl; 1209
nephrology image
calcium, 8.6 mg/dl; potassium, 3.5 mmol/l; uric acid, 5.4 mg/ dl; and normal intact parathyroid hormone and 25(OH) vitamin D levels. His urinary calcium, urate, and oxalate levels were normal. His urinary citrate level was toward the lower limit of normal. His 24-h urine protein was 664 mg, and 40–50 red blood cells (RBCs)/high power field with no RBC cast on urine microscopy were detected. His baseline urine pH was 7.15, serum HCO3 was 20.1 mmol/l, and serum pH was 7.31. Ammonium chloride loading test revealed a urine pH of 5.97, with serum HCO3 being 15.8 mmol/l at 3 h, consistent with distal renal tubular acidosis (dRTA). Urine anion gap was 26 mmol/l. Non-contrast computed tomography scan (Figure 2a) showed medullary calcific density consistent with nephrocalcinosis in the right kidney, and contrast study (Figure 2b) in early venous phase revealed bilateral dilated and tortuous renal veins with possible collateral formation (white arrow) and calcifications (black arrow).
1210
P Narayan et al.: Distal renal tubular acidosis
PS is a rare sporadic disorder of asymmetric overgrowth of body parts due to somatic mosaicism involving the AKT1 gene on 14q32.33, which has a key role in regulating cell survival, insulin signaling, angiogenesis, and tumor formation. It is characterized by vascular malformations of the capillary, venous, and lymphatic systems, as well as cerebriform connective tissue nevi, epidermal nevi, and dysregulated adipose tissue (lipoma). Less common features include cystic lung disease, ovarian/parotid adenomas, and craniofacial and genito-urinary abnormalities. Genitourinary abnormalities include undescended testis, renal asymmetry, renal failure, ureteric asymmetry, renal cysts, nephrogenic diabetes, hematuria, hydronephrosis, proteinuria, and hydroureter. The mechanism underlying dRTA in this patient is unknown, and further investigation of biochemical pathways in this area may confirm the association of PS and dRTA.
Kidney International (2013) 83, 1209–1210