Objective: To investigate the effect of age and gender on basal and food-stimulated serum calcitonin (CT), parathyroid hormone (PTH), and gastrin levels among healthy adults. Methods: Ninety-six healthy adults (76 men and 20 women) aged between 21 and 43 years were recruited. Serum CT, PTH, and gastrin levels were measured after a 9-hour overnight fast, and 1 and 3 hours postprandially. Results: PTH levels decreased early and increased late after feeding. This change was significant in men but not in women. CT levels increased in response to food intake in men but not in women. Gastrin levels were significantly increased after feeding in both men and women. Mean basal and food stimulated CT, PTH, and gastrin levels did not significantly differ between genders. Fasting and post-prandial PTH levels were higher while gastrin levels were lower in older subjects (>30 years old) compared to younger subjects (≤30 years old). Fasting and postprandial CT levels were not significantly different between age groups. Conclusion: Age had a significant effect on fasting and food-stimulated PTH and gastrin hormone levels. The effect of age on PTH levels was independent of baseline vitamin D levels. Men showed significant changes in CT and PTH levels in response to feeding compared to women, although the mean hormone levels were not significantly different between men and women. Abbreviations: CT = calcitonin; MTC = medullary thyroid carcinoma; PTH = parathyroid hormone; SD = standard deviation.