Case Quiz (February 2021)

          A 4 months old female was presented at the age of two months following her routine vaccination. She became lethargic and feeding poorly. She was admitted to a private hospital where her initial blood electrolytes showed subtle changes of hyponatremia and hyperkalemia, which settled following intravenous fluid infusion. Antibiotics were initially administered empirically and discontinued at 72 hrs after negative urine culture reports. She was discharged home on the fifth day. At 3 months old, she developed similar symptoms and was admitted. Her weight gain was satisfactory, but very recently her parents noticed a weight lag.
She was born from non consanguineous parents by CS; indication being previous sections. On the fetal anomaly scan conducted at 20 weeks of gestation, the left kidney was found to be slightly larger than the right one. But there was no follow up scan. The baby was born at term weighing 2.6 Kg. The neonatal period was uneventful. No apparent congenital anomaly was noted. After the initial few days of breast feeding, bottle feeding was commenced. While admitted to the pediatrics unit, the patient looked lethargic. Her heart rate was 115/min, respiratory rate was 38/min and capillary refill was less than 2 seconds. She was apyrexial with mild to moderate dehydration. Her blood pressure was 116/65 and both femoral pulses were palpable. Systemic examinations were normal with normal genitalia. Serum electrolytes revealed 121meq/l of sodium and 8.2meq/l of potassium. She was resuscitated with normal saline and also received simultaneous treatment for hyperkalemia. After the initial resuscitation, her serum potassium dropped to 7.4meq/l but she remained hyponatremic (120meq/l).

Her pH was 7.28 and serum HCO3 was 14 meq/l. Urinary sodium, chloride, potassium and calcium were abnormally high. Serum urea and creatinine were initially slightly raised but brisk improvement on IV fluids suggesting dehydration was the possible explanation. Her leukocyte count was 27,000/dl with neutrophil predominance; Hb was 9.6 gm%, Platelets count was 2450000/dl, C-reactive protein was 51 mg/l and Procalcitonine level was suggestive of systemic bacterial infection. Urinalysis showed high protein with protein creatinine ratio of 2. Urine was full of pus cells, and was positive for bacteria and nitrites. Serum hormone levels such as cortisol, Dyhydroepiandrosterone acetate (DHEA), adrenocorticotropic hormone (ACTH), 17-OH-progesterone, androstendione, thyroxin, all were within normal range.

Initial renal ultrasound scan showed normal right kidney and ureter. Her left kidney was enlarged and there was grossly dilated left ureter with debris suggesting pyelonephritis. The bladder was compressed by the grossly dilated left ureter. Both the ureters were abnormally inserted to the bladder at a lower level, right one being just distal to neck of the bladder into the urethra. Surprisingly, there was no evidence of any dribbling. Intravenous ceftriaxone was commenced for her UTI. MAG3 scan confirmed normal functioning right kidney, moderate impairment of function of the enlarged left kidney with hydronephrotic changes, hydroureter and evidence of organic obstructive uropathy at the left VUJ with abnormal insertion to the bladder.

Initial management was conducted with adequate saline infusion and correcting hyperkalemia with sodium bicarbonate, salbutamol nebulisation and calcium infusion. Later, the patient was kept on oral sodium supplements (15 mmol per day) maintaining normal electrolytes. She underwent left ureterostomy operation to facilitate the drainage. Postoperatively, she had another episode of UTI and was treated with intravenous Meropenem.

The patient was then planned for reconstructive surgery for reinsertion of both ureters which was conducted after 6 months of the primary procedure.

Diagnostic test was done

Case Answer (February 2021)

    Pseudohypoaldosteronism (PHA) type I  represents the most frequent form of primary PHA and is related to the loss of function of the mineralocorticoid receptor. The mode of inheritance is autosomal dominant with variable expression and related to the loss of function of the mineralocorticoid receptor.

The patient’s serum aldosterone level was very high (more than 2744 IU/l), confirming PHA. In the studied case, further investigation revealed obstructive uropathy as the original cause of the type IV RTA and pseudohypoaldosteronism. Bilateral obstructive uropathy is a well known cause of RTA type IV and PHA because of insensitivity of the aldosterone to the tubules. Acute pyelonephritis in the presence of urinary tract anomalies increases the
risk of PHA, although both factors independently can cause aldosterone unresponsiveness.

N.B. PHA type II, also recognized as Gordon’s Syndrome, it is thought to be a primary renal secretory defect that results from enhanced chloride reabsorption and consequent hyperkalemia, metabolic acidosis, and low-renin arterial hypertension. The normal serum chloride level in this patient was not in favor of this diagnosis