Cell cycle kinetics of human anagen scalp hair bulbs in thyroid disorders determined by DNA flow cytometry.

In both, 6 hyperthyroid and 6 hypothyroid patients as well as 10 healthy volunteers, cell cycle kinetics of dissected anagen scalp hair bulbs were determined by means of DNA flow cytometry (DNA-FCM). Compared with the healthy control group in patients with thyroid disorders striking differences of cell kinetic data were evaluated. In hyperthyroidism a significant increase (30%) and in hypothyroidism a significant decrease (15%) of S and G2+M phase cell percentages was found. The proliferation index (S+G2+M %) calculated revealed similar results. A correlation between the height of S phase percentages and plasma T3 levels was recognizable but could not be proven statistically. By means of DNA-FCM the study demonstrates for the first time the influence of thyroid hormones on in vivo cell cycle kinetics of human scalp hair bulbs.