Reversal of nocturnal non-dipping of blood pressure after Levothyroxine therapy in patients with subclinical hypothyroidism.

AIMS: To study the loss of diurnal variation in blood pressure in normotensive patients with Subclinical/overt hypothyroidism and effect of Levothyroxine (L-T4) treatment.

MATERIALS AND METHODS: In this interventional study Eighty patients between 17- 50 years with newly detected OH and SCH (74 women and 6 men) and nine euthyroid subjects (all men) with blood pressure <140/90 were recruited. All patients underwent 24h ambulatory blood pressure monitoring (ABPM) using ABPM machine before and after treatment with L-T4. Diurnal index (DI), Percent time elevation (PTE), Hyperbaric impact (HBI) were studied pre and post L-T4 treatment.

RESULTS: Of the 89 subjects (22 SCH, 58 OH and 9 controls), 7 of the SCH and 30 of OH subjects reported back in follow up after L-T4 supplementation for evaluation. DI, HBI and PTE when compared at baseline between different groups (SCH- OH, SCH- control, OH- control) were insignificant. After L-T4 supplementation DI, HBI and PTE varied significantly with p value 0.007, 0.003 and 0.003 respectively between SCH- OH only. Post L-T4 analysis in SCH group was statistically insignificant (p-value 0.102) but a trend toward improvement in DI was noted (baseline and post treatment DI mean 7.00 and 13.00 respectively).

CONCLUSION: Loss of nocturnal dipping was found in patients with OH and SCH which was restored after L-T4 therapy only in patients with SCH and not with OH.

TREATMENT: of SCH patients with high cardiovascular risk may be beneficial in this setting and can be a new indication for LT4 therapy in SCH.