Pseudohypoaldosteronism masquerading as congenital adrenal hyperplasia

Case report: Life threatening hyponatremia in infants with urinary tract infections: two cases of type III pseudohypoaldosteronism and review of the literature

We describe two female infants at the age of five and six months with urinary tract infections presenting with vomiting and reduced drinking behavior. On laboratory analysis, severe hyponatremia (106 mmol/L and 109 mmol/L) was seen with hyperkalemia and compensated metabolic acidosis. Endocrinological analyses revealed massively increased levels of aldosterone and renin, leading to the diagnosis of type III pseudohypoaldosteronism (PHA). A review of the current literature 2013-2023 revealed 26 type III PHA cases aged up to ten months with reduced drinking behavior, weight loss and/or failure to thrive being the most common clinical presentations. Given the severe presentation of PHA electrolyte measurements in infants with urinary tract infections and/or in infants with congenital anomalies of the kidney and urinary tract (CAKUT) are strongly recommended.

A novel SCNN1G mutation in a PHA I infant patient correlates with nephropathy

Systematic form of pseudohypoaldosteronism Type I (PHA I) is a rare recessive homozygous inherited syndrome characterized by severe salt loss, hyperkalemia, hyponatremia, metabolic acidosis, hyperaldosteronism and hyperreninemia. It is caused by mutations in one of the genes encoding the α, β and γ subunits of epithelial sodium channels (ENaC). In this study, we performed whole exome sequencing on an infant patient with PHA I as well as nephropathy. The result presented a novel homozygous six-base deletion in the γ subunit encoding gene SCNN1G. Then we correlated the mutant to kidney damage, along with transcriptional alterations of genes involved in inflammation, oxidative stress and apoptosis, via in vitro and in vivo tests. In addition, it was demonstrated that the SCNN1G defects triggered programmed cell death via inhibiting miR-21 and upregulating PTEN, which then orchestrated the key downstream regulators, including Bcl2, Bax2, and cleaved Caspse-3 in a way that favors cell apoptosis. The study enhances our understanding of the pathophysiology of the disorder of PHA I and the mechanisms of renal damage induced by the novel defect.

High aldosterone and cortisol levels in salt wasting congenital adrenal hyperplasia: a clinical conundrum

BACKGROUND

Salt wasting syndrome (hyponatremia, hyperkalemia, dehydration, metabolic acidosis) in early infancy could be caused by either mineralocorticoid deficiency as in congenital adrenal hyperplasia (CAH) and adrenal insufficiency or mineralocorticoid resistance as in pseudohypoaldosteronism (PHA). In salt wasting CAH, serum aldosterone and cortisol levels are expected to be low. Cross reactivity between high levels of adrenal steroid precursors and aldosterone has recently been reported resulting in elevated aldosterone levels in CAH, leading to difficulty in differentiating between CAH and PHA.

CASE PRESENTATION

We report four such cases of salt wasting CAH, where high aldosterone levels and high normal cortisol levels led to initial diagnostic confusion with PHA. Diagnosis of CAH was later established on the basis of significantly elevated adrenocorticotropic hormone (ACTH) stimulated 17-hydroxyprogesterone (17-OHP) values.

CONCLUSIONS

By reporting these cases we draw attention to the possibility that high levels of adrenal steroid precursors can cross react with aldosterone and cortisol, and underscore the significance of ACTH stimulated 17-OHP values in differentiating CAH and PHA.