Changes in serum homocysteine, lipid, vitamin B12, folate levels and glomerular filtration rate before and after treatment in overt hypothyroidism

F. Kutluturk; S. Yuce; T. Tasliyurt; B. Yelken; P. Aytan

Overt hypothyroidism is associated with an increased risk for cardiovascular disease. We aimed in this study, to assess the changes in renal function, serum lipids, vitamin B12, folate and homocysteine levels before and after treatment in hypothyroid patients.

Fifty-four (male/female;7/47) hypothyroid patients enrolled to study. We measured homocysteine(tHcy), total cholesterol(TC), triglyceride(TG), HDL-cholesterol (HDL-C), creatinine, folic acid, and vitamin B12 levels in both hypothyroid and euthyroid state. Table 1 summarizes the clinical and laboratory data of patients before and after L-T₄ replacement. Homocystein levels in hypothyroidism (9.67±5.24 mmol/l) were significantly higher than in euthyroid state (8.16±3.38 mmol/l, P=0.038). Serum creatinine was higher and GFR was lower before treatment. Following L-T₄ replacement, renal functions significantly improved. After achieving the euthyroid state, folate levels significantly increased although vitamin B12 remained unchanged. Serum lipids were significantly high before treatment. After L-T₄ replacement, lipid levels statistically significant decreased. We demonstrated a negative correlation between GFR and lipids and a positive correlation with tHcy and lipids in hypothyroid state. All of these correlations became not significant after L-T₄ replacement.

In conclusion, our study confirmed previous reports on the effects of thyroid status to cardiovascular risk factors namely hyperlipidemia and hyperhomocysteinemia. Furthermore, we concluded that, there was a strong correlation between serum lipids and both of GFR and tHcy in only hypothyroid status.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector

**Table 1** Clinical and laboratory characteristics of the patients in hypothyroid and euthyroid state.
	Hypothyroid state(n=54)	Euthyroid state(n=54)	P value
TSH (μIU/l)	37.05±34.15	2.32±1.55	<0.001
fT₄ (ng/dl)	0.64±0.33	1.31±0.29	<0.001
Creatinine (mg/dl)	0.78±0.23	0.68±0.13	<0.001
Homocysteine (μmol/l)	9.67±5.24	8.16±3.38	0.038
GFR (ml/min)	98.42±24.32	111.48±20.79	<0.001
Total cholesterol (mg/dl)	227.75±56.56	196.92±36.34	<0.001
LDL-C (mg/dl)	140.97±45.32	115.37±33.01	<0.001
HDL-C (mg/dl)	52.94±16.35	48.83±15.72	0.001
Folate (ng/ml)	7.61±2.76	8.53±3.19	0.017

Endocrine Abstracts

P1673