Primary renal tubular acidosis during pregnancy, what about the perinatal prognosis? A case report and literature review

Abstract

Renal tubular acidosis (RTA) is a group of disorders caused by tubular defects leading to defective reabsorption of bicarbonate (HCO₃⁻) and/or secretion of protons (H⁺). It is known that pregnancy can induce or worsen some forms of RTA. To date, no systematic data exist on the course of pregnancy in hereditary RTA-affected mothers, nor on the outcome of both mothers and children.

A 35-year-old female patient attends her routine obstetric follow-up consultation at 32-weeks’ pregnancy. From the 6th week of gestation, she has been complaining of general malaise, accompanied by paraesthesia in both hands. She is known to have renal tubular acidosis type 1, carrying a mutation in the SLC4A1 gene encoding for the bicarbonate-chloride exchanger located in the alpha-intercalated cell of the renal collecting tubule. At week 32, serum bicarbonate levels appeared to be 11 mEq/l. The patient was hospitalised and treated with intravenous sodium bicarbonate and potassium chloride. After 5 days, the symptoms resolved, and her bicarbonate level had normalised. A healthy infant was born with a normal Apgar score. Carriage of the same mutation was found in the child at 16 months. Our literature study shows that 12 of the 13 reported infants born from a mother with primary RTA were healthy at delivery. One neonate revealed signs of hyperparathyroidism at day 2, but those signs resolved at 1 month of age.

RTA during pregnancy is often associated with decompensation and worsening of acidosis. More attention should be paid to patients with RTA suffering from hyperemesis gravidas, in particular regarding therapy adherence. Our literature review focusses on foetal prognosis, which seems to be favourable in most of the reported pregnancies.