Serum cystatin C is sensitive to small changes in thyroid function

Clin Chim Acta. 2003 Dec;338(1-2):87-90. doi: 10.1016/j.cccn.2003.07.022.


Background: Serum cystatin C (CysC) is a novel marker for kidney function. The impact of mild thyroid dysfunction on CysC has never been investigated.

Methods: CysC was determined at the time of diagnosis of subclinical hypo- and hyperthyroidism, and when TSH returned into the normal range in 40 consecutive patients with mild thyroid dysfunction.

Results: Twenty-six patients with subclinical hypothyroidism and 14 patients with subclinical hyperthyroidism were included. In patients with subclinical hypothyroidism median (range) TSH was 7.8 (4.3-26.7) mU/l (reference 0.27-4.2) at diagnosis and decreased to 2.3 (0.36-4.0) mU/l following treatment with levothyroxine. Mean (+/-S.D.) CysC increased from 0.88+/-0.23 mg/l (reference 0.63-1.33) in the hypothyroid state to 1.01+/-0.21 mg/l when TSH normalized (p<0.001). In patients with subclinical hyperthyroidism, median TSH at diagnosis was 0.08 (0.001-0.26) mU/l and increased to 1.6 (0.28-4.0) mU/l in the euthyroid state. CysC declined from 1.04+/-0.29 mg/l at diagnosis of subclinical hyperthyroidism to 0.91+/-0.25 mg/l when TSH normalized (p<0.05).

Conclusions: Mild thyroid dysfunction significantly alters CysC levels. Therefore, thyroid function has to be considered when CysC is used as a marker of kidney function.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Cystatin C
  • Cystatins / blood*
  • Female
  • Humans
  • Hyperthyroidism / blood*
  • Hyperthyroidism / diagnosis
  • Hyperthyroidism / physiopathology*
  • Male
  • Middle Aged
  • Thyroid Function Tests
  • Thyroid Gland / physiopathology*


  • CST3 protein, human
  • Cystatin C
  • Cystatins