Early Childhood Hyperkalemia: Variety of Pseudohypoaldosteronism

Abstract

Fractional excretion of electrolytes, renal acidification capacity and the renin-aldosterone system have been studied in 5 non-azotemic children, 19-25 months old, with mineralocorticoid resistant hyperkalemia, discovered in the first month of life. Although fractional potassium excretion was similar in patients and in a group of control healthy children (13.8 +/- 5.2% vs. 8.7 +/- 6.4%) it was inappropriately low in the patients for their higher potassium concentration. Fractional sodium excretion was significantly increased in the patients (1.6 +/- 0.3% vs. 0.67 +/- 0.4, p less than 0.02). Normal net acid and ammonium excretion and intact ability to lower urinary pH during acid loading were observed in all patients. Mean values for plasma aldosterone (37.0 +/- 9.1 vs. 13.9 +/- 11.2 ng/dl), plasma renin activity (12.5 +/- 3.9 vs. 8 +/- 2.8 ng/ml/h) and plasma aldosterone/plasma potassium ratio (7.11 +/- 1.5 vs. 3.08 +/- 1.7) were higher in the patients than in the control subjects (all p less than 0.001). These data support the hypothesis that a partial lack of response of the renal tubule to endogenous mineralocorticoids was present in the patients. This type of pseudohypoaldosteronism is less severe than that described for the classic form and for early childhood renal acidosis.

Renal Genetic Disorders Related to K+ and Mg2+

“…In 1991, a distinction was made by Hanukoglu between a severe, multisystem syndrome, which appeared to be autosomal-recessive, and a dominant form that was primarily associated with hyperkalemia (124). Other reports had described such cases of childhood hyperkalemia without the severe salt wasting that is characteristic of the recessive form of the syndrome (125,126). In retrospect, it appears that some degree of confusion initially resulted from studies of Type I mineralocorticoid receptor abundance and binding characteristics in peripheral blood monocytes (127,128), and the apparent lack of mutation in the mineralocorticoid receptor (129,130).…”

Renal Tubular Acidosis

“…A transient syndrome of hyperkalemia and metabolic acidosis, without clinical saltwasting, has been described in infancy. Plasma renin activity and aldosterone excretion were consistently normal or elevated (46). This entity has been called "early-childhood" hyperkalemia and represents a variant of the renal form of pseudohypoaldosteronism type 1, probably due to a maturation disorder in the number or function of mineralocorticoid receptors.…”

New insights into the pathogenesis of renal tubular acidosis - from functional to molecular studies

“…Plasma renin activity and aldosterone excretion were consistently normal or elevated [154,155]. This entity has been called "early-childhood" hyperkalemia and represents a variant of the renal form of PHA1 probably due to a maturation disorder in the number or function of mineralocorticoid receptors.…”