Hypothyroidism is associated with reversible decline in kidney function as measured by estimated glomerular filtration rate (eGFR). eGFR and proteinuria are most important markers for clinical assessment of kidney function. Though hypothyroidism is associated with proteinuria in cross sectional data, the impact of treatment on proteinuria is unknown.
The study explores the effect of thyroid hormone replacement therapy on eGFR and 24-hour urine protein excretion in patients with severe primary hypothyroidism.
The study was a prospective, observational cohort study in adult subjects with severe primary hypothyroidism (serum TSH >50 µIU/mL). Subjects with pre-existing or past kidney disease, kidney or urinary tract abnormalities, calculi or surgery, diabetes mellitus or hypertension were excluded. The participants received thyroid hormone replacement therapy. Thyroid functions, eGFR, 24-hour urine protein excretion and biochemical parameters were measured at baseline and 3 months.
Single center, tertiary care referral and teaching hospital.
Out of 44 enrolled participants, 43 completed 3 months of follow up. At 3 months, serum TSH levels decreased and T4 levels increased (p<0.001 for both). Significant increase in eGFR (mean difference: 18.25±19.49ml/min/1.73m 2, 95% CI: 12.25 to 24.25, p<0.001) and decline in 24-hour urine protein excretion (mean difference: -68.39±125.89 mg/day, 95% CI: -107.14 to -29.65, p=0.001) were observed. Serum cholesterol and LDL levels also significantly decreased (p<0.001).
Thyroid hormone replacement therapy in patients with severe primary hypothyroidism improves eGFR and decreases 24-hour urine protein excretion, thereby suggesting reversible alterations.

© The Author(s) 2020. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.