Relationship between Hypothyroidism and Serum Calcium, Magnesium, and Phosphorous Levels

Open Access

Abstract

Background: Hypothyroidism is a common endocrine disorder associated with multiple metabolic abnormalities, including disturbances in mineral metabolism. Thyroid hormones play an essential role in bone remodeling, renal handling, and intestinal absorption of minerals such as calcium, magnesium, and phosphorous. Alterations in these minerals may contribute to neuromuscular symptoms, bone disease, and cardiovascular complications in hypothyroid patients. However, serum mineral levels are often overlooked in routine evaluation. Objectives: The present study aimed to assess serum calcium, magnesium, and phosphorous levels in patients with hypothyroidism and to determine their relationship with the severity of thyroid dysfunction as indicated by thyroid-stimulating hormone (TSH) levels. Methods & Materials: This hospital-based cross-sectional observational study was conducted in a Department of Biochemistry, National Institute of Diseases of the chest and Hospital, Mohakhali, Dhaka, Bangladesh from January to December 2023 and included 80 adult patients with biochemically confirmed hypothyroidism. Patients with conditions or medications affecting mineral metabolism were excluded. Fasting venous blood samples were collected for estimation of serum TSH, free thyroxine (FT4), calcium, magnesium, and phosphorous using standard biochemical methods. Data were analyzed using statistical software, and correlations between TSH and mineral parameters were evaluated. A p-value <0.05 was considered statistically significant. Results: The mean age of the study population was 41.6 ± 12.4 years, with a female predominance (72.5%). The mean serum TSH level was 18.6 ± 7.9 mIU/L. Mean serum calcium (8.21 ± 0.62 mg/dL) and magnesium (1.61 ± 0.28 mg/dL) levels were lower than normal reference ranges, while mean serum phosphorous level (4.92 ± 0.74 mg/dL) was elevated. Hypocalcemia, hypomagnesemia, and hyperphosphatemia were observed in 56.3%, 48.8%, and 52.5% of patients, respectively. Serum calcium and magnesium showed significant negative correlations with TSH, whereas serum phosphorous demonstrated a significant positive correlation. Conclusion: Hypothyroidism is associated with significant alterations in serum calcium, magnesium, and phosphorous levels, and these changes correlate with disease severity. Routine monitoring of mineral parameters may help in early identification and management of metabolic complications in hypothyroid patients.