Gender, Anaemia, and Azotaemia as Correlates of Thyroid Dysfunction in Chronic Kidney Disease: A Cross-Sectional Study From North India.

Background and objective Thyroid dysfunction is a well-recognised but under-investigated complication of chronic kidney disease (CKD). While the overall prevalence of hypothyroidism in CKD is documented, its association with specific clinical variables, particularly including gender, haemoglobin (Hb), and azotaemia, has not been systematically characterised in populations from the Indian subcontinent. Hence, this study was designed to identify the correlates of thyroid dysfunction in CKD patients on conservative management. Methods A cross-sectional observational study was conducted involving 100 CKD patients (age ≥ 18 years) attending the outpatient and inpatient wards of Dr. Baba Saheb Ambedkar Medical College and Hospital (Dr. BSAH), New Delhi, between 2019 and 2021. Patients on dialysis, those with nephrotic syndrome, pregnancy, liver disease, or medications known to alter thyroid function were excluded. CKD was staged using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria and the four-variable Modification of Diet in Renal Disease (MDRD) formula. Serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were measured by an enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed using IBM SPSS Statistics version 20 (IBM Corp., Armonk, NY), employing the chi-square test, one-way analysis of variance (ANOVA), the independent samples t-test, the Pearson correlation, and binary odds ratio (OR) calculation. Results The mean age of the cohort was 51.32 ± 11.89 years; 72 (72%) were male and 28 (28%) female. CKD stage 5 was the most common stage (44 (44%)). Total hypothyroidism prevalence was 46% (subclinical hypothyroidism (SCH): 24 (24%), overt hypothyroidism (OH): 22 (22%), low T3 syndrome: nine (9%)). Female patients had a significantly higher hypothyroidism rate (20 (71.4%) vs 26 (36.1%); χ² = 10.335, OR = 4.42, 95% CI: 1.71-11.44, p = 0.003) and higher mean TSH (5.84 vs 4.41 μIU/ml; t = -2.116, p = 0.036). Overt hypothyroidism was associated with the lowest Hb (7.97 g/dl; ANOVA F = 6.349, p = 0.001) and the highest blood urea (152.03 mg/dl; ANOVA F = 3.24, p = 0.024). Hb correlated negatively with TSH (r = -0.236, p = 0.018) and positively with estimated glomerular filtration rate (eGFR) (r = 0.516, p < 0.001). Advanced CKD stage 5 was significantly associated with a higher risk of hypothyroidism (OR = 2.60, 95% CI: 1.15-5.85, p = 0.034). Comorbidities (type 2 diabetes mellitus (T2DM), hypertension (HTN)) and age were not significantly associated with thyroid dysfunction. Conclusions Female gender and advanced CKD stage show the strongest associations with hypothyroidism in this cohort. Overt hypothyroidism is associated with more severe anaemia and higher azotaemia, beyond what is explained by CKD stage alone. These findings support targeted thyroid function testing in CKD patients; prospective studies are warranted to establish the clinical benefit of such a strategy.