Level of cystatin C in functional thyroid disorders and its relation to GFR

Abstract

Thyroid hormones affect the development and physiology of the kidneys. Hypothyroidism and hyperthyroidism affect glomerular filtration rate (GFR), tubular function, renal blood flow, and structure of the kidney. Cystatin C is a non-glycosylated neuroendocrine protein. It is freely filtered at the glomerulus and completely reabsorbed and catabolized by cells of tubules. Cystatin C levels, affected by the thyroid state, is being increased in hyperthyroidism and decreased in hypothyroidism. The current study was conducted on 66 patients of thyroid disorder and 21 healthy control subjects. Total T3, total T4, and TSH were measured by cobas e 411. Human Cystatin C was measured using ELISA kit based on sandwich enzyme-linked immunosorbent assay. Cystatin C was significantly increased in both total hyperthyroid and clinical hyperthyroid groups as compared to control (p < 0.001). eGFRCys C and eGFRCr-Cys C were significantly decreased in hyperthyroid and clinical hyperthyroid (p < 0.001). Cystatin C was significantly reduced in hypothyroid group and subgroups comparing to control group (p < 0.001, p < 0.001, and p = 0.004, respectively). As regard to eGFRCys C, it was significantly an overestimate clearance in hypothyroid group and subgroups when compared to normal subjects (p < 0.001, p < 0.001, and p = 0.002, respectively). Thyroid dysfunction affects cystatin C level as well as cystatin-based eGFR so it is not suitable in thyroid dysfunction specially in clinical dysfunction.