Introduction: Thyroid hormone is a central regulator of body hemodynamics, thermoregulation, and metabolic functions and in the disorders of the thyroid gland, signs and symptoms are often nonspecific. Both subclinical hypothyroidism and hyperthyroidism are associated with an increased risk of disease and alteration in biochemical and physiologic measures. In severe hypothyroidism and myxoedema, hyponatremia was a consequence of enhanced renal water retention mediated by vasopressin. Lactate dehydrogenase (LDH) is an enzyme found in nearly all living cells. It catalyzes the conversion of lactate to pyruvate and back, as it converts NAD+to NADH. However, only a few studies have investigated serum lactate dehydrogenase activity in patients with thyroid dysfunction. Vitamin D acts likea steroid hormone and is presently considered an immunomodulator affecting a wide range of functions. Aim and Objectives: To estimate the levels of serum electrolytes like sodium, potassium magnesium, LDH, and vitamin D in hypothyroid patients and to correlate with TSH. Materials and methods: The study population was serum specimens from 150 patients with hypothyroidism with ages ranging from 25-65 years. The samples were collected from the Thyroid laboratory, Department of Biochemistry, PGIMS, Rohtak. The different parameters of the study were estimated on the electrolyte analyzer, autoanalyzer, and radioimmunoassay. Results and conclusion: The mean values for Na, K, Mg, LDH, and vitamin D were found to be 128.13±5.09, 3.01±0.25, 1.87±0.32, 604.89±175.79, and 7.48±1.61, respectively. Our findings support that hypothyroid patients have subtle disturbances of electrolytes, LDH and vitamin D levels.