IMPE Abstracts

Pseudohypoaldosteronism (PHA) is a rare heterogeneous mineralocorticoid resistance syndrome caused by insufficient potassium and hydrogen secretion. PHA type1 (PHA1) causes neonatal salt loss, failure to thrive, dehydration, and circulatory shock. Two different forms of PHA1 can be distinguished on the clinical and genetic levels, showing either a systemic or a renal form. We present an infant with a clinical diagnosis of PHA1. A male 39-week newborn, presented on postnatal-day 14 with hyperbilirubinemia, severe dehydration, and polyuria. He was lethargic, hypoactive, floppy, tachycardic, and tachypneic, with normal blood pressure. Medical history, the first child of non-consanguineous parents without perinatal asphyxia or TORCH infection. Cousin with neonatal hypokalaemia, no other family history. Weight and height at birth were 3,150g (–0.46 SD) and 50cm (–0.10 SD) respectively. Admission weight (3,185g) suggested a 10% loss of total body weight in the first week with 25g/day gain after. No skin hyperpigmentation, abnormal genital, or systemic alteration was observed. Laboratory tests revealed severe hyponatremia, hyperkalemia, and metabolic acidosis, other tests discarded infection, and renal injury. Additionally with total hyperbilirubinemia at 20.31mg/dL, direct at 1.54mg/dL, and GGT at 227u/L with normal transaminases and abdominal ultrasound. Following the immediate collection of critical blood samples, fluid and electrolyte resuscitation was performed. However, hyperkalemia and hyponatremia persisted despite supportive therapies. Transferred to PICU at 19 days of life due to severe hyperkalemia (10.57mmol/L) with peaked T-wave on electrocardiogram and severe hyponatremia (111.6mmol/L). Hyperkalemia was corrected using insulin and glucose infusion, calcium gluconate, inhaled salbutamol, and bicarbonate infusion, and hyponatremia required hypertonic saline 3% and fludrocortisone. After starting polarizing solution, a single convulsive event was present due to hypoglycemia, adjusting metabolic flow. Plasma adrenocorticotropic hormone, cortisol, and adrenal androgens were reported normal. Elevated plasm renin (>500uUI/ml) and aldosterone (>1400pg/ml) suggested a diagnosis of PHA1. Normokalemia and eunatremia were achieved with oral salt replacement (5g/day) and fludrocortisone was progressively stopped. A genetic panel was performed, pending report. Aldosterone activates the mineralocorticoid receptor (MR) inducing a response in the sodium channel (ENaC) necessary for its conservation. MR is coded by the NR3C2 gene localized on chromosome 4q31.1 and is composed of ten exons. Disruption of the intracellular MR signaling pathways leads to the clinical entity of PHA. The presence of hyperkalemia, hyponatremia, metabolic acidosis, and elevated plasma aldosterone levels lead to the suspicion of PHA, mainly in patients with poor response to supportive therapy. Genetic confirmation is necessary to carry out the counseling.