Renal Tubular Acidosis in Pregnant Critically Ill COVID-19 Patients: A Secondary Analysis of a Prospective Cohort.

BACKGROUND

Renal tubular acidosis (RTA) is an extremely rare cause of metabolic acidosis (10 in 100,000). RTA has been linked neither to pregnancy nor to severe coronavirus disease 2019 (COVID-19). The purpose of this study was to analyze the prevalence and clinical course of normal anion gap metabolic acidosis in critically ill pregnant COVID-19 patients and to compare them to an age-matched nonpregnant female patient cohort.

METHODS

Secondary analysis was conducted on a prospective observational cohort of critically ill patients suffering from COVID-19 consecutively admitted to a tertiary intensive care unit (ICU) between February 2020 and April 2021.

RESULTS

A total of 321 COVID-19 patients required admission to the ICU; 95 (30%) were female, and 18 (19%) were of childbearing age. Seven of eight (88%) pregnant women (all in the last trimester) required advanced respiratory support due to COVID-19. The estimated glomerular filtration rate was 135 (123-158) mL/min/m body surface area, and six pregnant women (86%) were diagnosed with a normal, respiratory compensated, anion gap metabolic acidosis (pH 7.3 (7.18-7.31), HCO 14.8 (12.8-18.6) mmol/L, and paCO 3.4 (3.3-4.5) kPa). Three (43%) acidotic pregnant women fulfilled diagnostic criteria for RTA. All women recovered spontaneously within less 7 days.

CONCLUSIONS

Metabolic acidosis seems to be very common (85%) in pregnant critically ill COVID-19 patients, and the prevalence of RTA might be higher than normal. It remains to be demonstrated if this observation is an indirect epiphenomenon or due to a direct viral effect on the tubular epithelium.