Presence or severity of Hashimoto's thyroiditis does not influence basal calcitonin levels: observations from CROHT biobank.

No significant difference in median basal calcitonin levels was detected between Hashimoto's thyroiditis patients and control participants.

• Median Ct levels were 2.2 pg/mL in HT patients vs 2.35 pg/mL in controls (P = 0.717)
• Study included 467 HT patients and 184 control participants from the Croatian Biobank of HT patients (CROHT)
• Mann-Whitney test was used for comparison
• This was a retrospective study design

Calcitonin levels did not differ significantly between HT patient subgroups divided by levothyroxine therapy intake, used as a proxy for illness severity.

• Comparison between two subgroups of HT patients (with and without LT4 therapy) yielded P = 0.347
• LT4 therapy intake was used to account for illness severity
• No statistically significant difference was found between the subgroups

No statistically significant correlations were detected between calcitonin levels and 14 clinical phenotypes of HT patients, though three weak nominal correlations were identified.

• Spearman rank correlation test was used to analyze correlations between Ct levels and 14 relevant phenotypes
• A negative correlation of Ct with TgAb was observed in all HT patients (r = -0.1, P = 0.04)
• A negative correlation of Ct with age was observed in the subgroup of HT patients without LT4 therapy (r = -0.13, P = 0.04)
• A positive correlation of Ct with BSA (body surface area) was observed in the subgroup of HT patients on LT4 therapy (r = 0.16, P = 0.042)
• The authors note these are weak nominal correlations requiring additional confirmation

The authors concluded there is no need for calcitonin measurements in HT patients in the absence of a thyroid nodule.

• Results suggest HT patients at all disease stages preserve Ct production similarly to healthy individuals
• Additional confirmation and clarification of observed nominal correlations are needed due to potential clinical relevance of TgAb and age-dependent Ct decrease in HT women