In thyroxine-replaced hypothyroid postmenopausal women under simultaneous calcium supplementation, switch to oral liquid or softgel capsule L-thyroxine ensures lower serum TSH levels and favorable effects on blood pressure, total cholesterolemia and glycemia.

PURPOSE: In postmenopausal women under L-T4 therapy, which was subsequently accompanied by calcium carbonate (CC) supplementation taken 6-8 h after tablet L-T4, TSH levels were greater than prior to adding CC. Total cholesterolemia [CHOL], fasting glycemia [FG], systolic and diastolic blood pressure [SBP, DBP] were also greater than baseline. Our aim was to explore the effects of either liquid or softgel capsule L-T4, while maintaining CC ingestion 6-8 h, later on TSH levels, CHOL, FG, SBP, and DBP.

METHODS

We proposed to 50 hypothyroid postmenopausal women under tablet L-T4 therapy, to switch to either liquid or softgel capsule L-T4 at the same daily dose while maintaining CC ingestion 6-8 h later. Sixteen women accepted [group I; liquid (n = 9), capsule (n = 7)], while 34 continued tablet L-T4 [group II, (n = 34)].

RESULTS

After 3 months, in group I, TSH decreased significantly (1.23 ± 0.49 vs. 1.80 ± 0.37 mU/L, P < 0.01), as did FG (80.7 ± 7.9 vs. 83.4 ± 6.3 mg/dL, P < 0.05); CHOL, SBP, and DBP decreased, though insignificantly. In contrast, in group II, TSH, FG, CHOL, SBP increased insignificantly, and DBP increased borderline significantly (69.7 ± 9 vs. 66.3 ± 6.5, P < 0.10). Compared to baseline (before adding CC), in group I, TSH was significantly lower (P < 0.01) and the other indices similar; in group II, TSH, FG, and SBP were significantly higher (P < 0.05), DBP borderline significantly higher (P < 0.10) and CHOL insignificantly higher. Performance of liquid L-T4 and capsule L-T4 was similar.

CONCLUSION

Delaying CC ingestion even by 6-8 h after taking tablet L-T4 is not entirely satisfactory, unlike liquid or softgel L-T4.