LAUSR

A girl aged 6 years applied to the Pediatric Nephrology outpatient facility with growth retardation. She was previously diagnosed with Bartter syndrome from a local city hospital based on polyuria, polydipsia, hyponatremia, hypochloremia, hypokalemia, and metabolic alkalosis. She was taking indomethacin (5 mg/kg/day), oral potassium chloride (1 mEq/kg/day), and oral magnesium oxide (40 mg/kg/ day). Her past medical history showed that she was born by spontaneous vaginal delivery at term with a birth weight of 3,300 g (25th to 50th percentile). She had multiple hospitalizations due to feeding difficulties and vomiting. At 7 months of age, she was diagnosed with Bartter syndrome (BS). Her parents were first-degree cousins, and they had two other daughters and a son; all were alive and well. The parents mentioned that their cousin also had kidney failure and kidney transplantation, but they did not know her primary disease. On physical examination, the patient had severe short stature and malnutrition with a height of 81 cm (-6.88 SDS) and a weight of 9.2 kg (-5.92 SDS). Blood pressure was 90/53 mmHg (75th percentile), pulse rate was 90 beats/ min, and her temperature was 36.5° C. She had dark hair, brown eyes, coarse facial features, and frontal bossing. There was no clinical sign of dehydration. The cardiovascular and respiratory systems were normal. She had rachitic rosary, increased anteroposterior chest diameter, and abdominal distention without hepatomegaly or splenomegaly. X-bain deformity in lower extremities and wide wrists were noted. Cognitive functions appeared normal. Biochemical, endocrine, and metabolic investigations are listed in Table 1. Estimated glomerular filtration rate (eGFR) was 73 mL/min/1.73 m2, which revealed Stage 2 chronic kidney disease (CKD). Hyponatremia, hypochloremia, hypokalemia, hypophosphatemia, and hyperuricemia with mild metabolic alkalosis were found. She had normal serum albumin and lipid levels. Alkaline phosphatase (ALP) and parathyroid hormone (PTH) levels were high, while serum 25-hydroxyvitamin D level was low. Because of this, vitamin D 6,000 IU was started. Also, impaired thyroid function tests indicating hypothyroidism were detected, and L-thyroxine replacement with a dose of 25 mcg was started. Urinalysis showed a specific gravity of 1004 and a pH level of 6.5 with proteinuria (+ +) and glucosuria ( ±). Microscopic examination of the urine sediment was normal. Urine culture did not reveal any bacterial growth. Tubular functional tests also showed high fractional excretions of sodium and potassium (2.7% and 69%, respectively) and low tubular phosphate reabsorption (53%) with a normal ratio of tubular maximum reabsorption of phosphate (TmP) to GFR (4.09 mg/dL). Twenty-four-hour urine volume was 2,250 mL/day (10.3 mL/kg/hour), indicating polyuria. She had nephrotic range proteinuria (200 mg/m2/hour), glycosuria (495 mg/day), and hypercalciuria (4.7 mg/kg/day) (Table 1). Kidney ultrasonography showed no urinary stone or nephrocalcinosis, but it detected bilateral grade 1 hyperechogenic kidneys with normal corticomedullary differentiation The answers to these questions can be found at https:// doi. org/ 10. 1007/ s0046702105384-2