Thyroid function in patients with idiopathic nephrotic syndrome

Albumin is the major protein excreted in urine in patients with nephrotic syndrome (NS). However, low-molecular-weight proteins including some binding proteins are also excreted. Thyroid hormone and its binding globulins are excreted in urine in excess in nephrotic syndrome. Therefore, it has been postulated that patients with nephrotic syndrome may show hypothyroidism, subclinical or overt.

In this prospective observational study, patients of idiopathic nephrotic syndrome aged 1-40 years of both gender were included. Serum T3, T4 and TSH were assayed at diagnosis and repeated at 12 weeks or at remission whichever was earlier. Renal biopsy was performed as required.

Among 100 patients taken for analysis (42 children, 58 adult), 30 cases were of first episode, 40 were of frequent relapse/steroid-dependent NS, and 30 patients had steroid-resistant NS (SRNS). Three (3%) cases had overt hypothyroidism and 18 (18%) patients had subclinical hypothyroidism. Most hypothyroid cases belonged to SRNS subgroup. Mean Serum T3, T4 and TSH values showed significant improvement in remission in comparison to nephrosis state (P < 0.01). Serum TSH had significant positive correlation (r = 0.391, P < 0.01) with 24-h proteinuria and negative correlation with serum albumin (r =  - 0.303, P < 0.01) in nephrosis.

Hypothyroidism is common among nephrotic syndrome patients especially in SRNS subgroup. Therefore, routine screening is recommended in steroid-resistant nephrotic syndrome patients.