Abstract
Objective Although thiazide diuretics are commonly used in the neonatal intensive care unit
(NICU), the risk of thiazide-induced hyponatremia in infants has not been well documented.
The primary objective of this study was to determine the frequency and severity of
hyponatremia in neonates and infants receiving enteral chlorothiazide. Secondary objectives
included identifying: (1) percent change in serum sodium from before chlorothiazide
initiation to nadir, (2) time to reach nadir serum sodium concentration, and (3) percentage
of patients on chlorothiazide receiving sodium supplementation.
Study Design This was a retrospective cohort study of NICU patients admitted between July 1, 2014,
and July 31, 2019, who received ≥1 dose of enteral chlorothiazide. Mild, moderate,
and severe hyponatremia were defined as serum sodium of 130 to 134 mEq/L, 120 to 129 mEq/L,
and less than 120 mEq/L, respectively. Data including serum electrolytes, chlorothiazide
dosing, and sodium supplementation were collected for the first 2 weeks of therapy.
Descriptive and inferential statistics were performed in SAS software, Version 9.4.
Results One hundred and seven patients, receiving 127 chlorothiazide courses, were included.
The median gestational age at birth and postmenstrual age at initiation were 26.0
and 35.9 weeks, respectively. The overall frequency of hyponatremia was 35.4% (45/127
courses). Mild, moderate, and severe hyponatremia were reported in 27 (21.3%), 16
(12.6%), and 2 (1.6%) courses. The median percent decrease in serum sodium from baseline
to nadir was 2.9%, and the median time to nadir sodium was 5 days. Enteral sodium
supplements were administered in 52 (40.9%) courses. Sixteen courses (12.6%) were
discontinued within the first 14 days of therapy due to hyponatremia.
Conclusion Hyponatremia occurred in over 35% of courses of enteral chlorothiazide in neonates
and infants. Given the high frequency of hyponatremia, serum sodium should be monitored
closely in infants receiving chlorothiazide. Providers should consider early initiation
of sodium supplements if warranted.
Key Points
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One-third of infants on chlorothiazide develop hyponatremia.
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Nadir serum sodium typically occurs within 5 days.
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Monitor sodium closely after chlorothiazide initiation.
Keywords
chlorothiazide - hyponatremia - NICU
