CHANGES IN TSH AND LIPID LEVELS AFTER COMMENCING TREATMENT FOR HYPOTHYROIDISM

Abstract

Objective: The significance of dyslipidemia in subclinical hypothyroidism (SCH) and the effect of thyroid substitution on lipids remain controversial. The present study aimed to assess the association of SCH with lipid abnormalities and to quantify the effect of L-thyroxin therapy on serum lipid profiles. This work will also suggest new strategy for treatment of hypothyroidism.

Design: Serum lipid parameters of 50 patients with SCH and 100 euthyroid controls were evaluated in a cross-sectional study.

Results: The levels of patients of SCH were compared with levels observed in 100 normal persons. The overall observed Mean ±SEM of T3, T4, TSH levels before treatment were: 2.06±0.12 nmol/L, 88.8±6.53 nmol/L 40±7 µIU/ml. Cholesterol, triglycerides, HDL and LDL levels were 208.5±7.98 mg/dl, 154.7±16.9 mg/dl, 26.73±3.3 mg/dl and 137.5±7.75 mg/dl respectively. After treatment with thyroxin 100μg of daily dose the Mean ±SEM of T3, T4, and TSH were 2.14±0.09 nmol/L, 116.8±7.8 nmol/L and 12.37±3.37µIU/ml. Lipid profile levels after treatment were 174.6±10.5 mg/dl, 161.3±22.9 mg/dl, 20±1.99 mg/dl and 125.5±9.8 mg/dl respectively. Overall comparison of hormone and lipid levels in patients of SCH. with those in normal persons showed that T3 and T4 were within normal range although T4 levels were significantly high compared to normal persons (P<0.05). TSH was significantly high in SCH. (P<0.001) when compared with normal controls. Cholesterol, HDL and LDL levels were significantly raised in SCH patients (P<0.001 & P<0.05 respectively) whereas triglyceride values were not significantly different from normal persons (P>0.05). T3 remained almost unaffected after one month of thyroxin replacement therapy; T4 levels showed an increase in level but remained within the normal range. Whereas TSH values were significantly reduced (P<0.05) reached close to the upper normal limit. Data  of hormones and lipid levels obtained after two months of therapy was similar to that observed after one month therapy however, there was a steady decrease in TSH levels (P<0.001). After three months of thyroxin replacement therapy, T3 levels again remained unaffected (P>0.05), T4 levels were  seemed stabilized and within normal range whereas TSH values were at upper border of normal range. During the follow up the levels of lipid profile shows same order i.e. there is no significant change in triglyceride, HDL and LDL but total cholesterol levels were significantly decreased.

Conclusion:

We concluded that thyroxin replacement therapy (100μg thyroxin daily dose) affects T4, TSH and cholesterol levels. T4 is increased relative to pretreatment values but remains within normal limits. TSH is reduced gradually as the treatment proceeds. Cholesterol levels decrease significantly in most of cases with the duration of treatment. However other lipids remain almost unaffected after three months of thyroxin replacement therapy.

Key Words:

Subclinical hypothyroidism, Dyslipidemia, euthyroid, thyroxin