Vitamin Level Testing for Patients on Zepbound with Significant Weight Loss and Fatigue

Primary Vitamin Panels to Check

A complete B-vitamin panel, including B12, folate, and B6, should be checked in patients on Zepbound experiencing fatigue and significant weight loss, as deficiencies can contribute to fatigue and are common with reduced food intake, according to the Proceedings of the Nutrition Society and Obesity Reviews 1, 2
Vitamin D levels should be checked, along with calcium, phosphate, magnesium, and PTH, as vitamin D deficiency is prevalent in weight loss patients and can contribute to fatigue, as noted by Obesity Reviews and Sports Medicine 3, 4
Iron studies, including serum ferritin, transferrin saturation, and complete blood count, should be assessed to detect iron deficiency anemia, which is a common cause of fatigue, especially in females with reduced food intake, as reported by Obesity Reviews and the Journal of the National Comprehensive Cancer Network 2, 5
Trace minerals, including zinc, copper, and selenium, should be tested, as unexplained fatigue may be related to deficiencies in these micronutrients, according to Obesity Reviews 2, 3

The American College of Nutrition recommends checking vitamin D levels, as levels below 50 nmol/L are considered inadequate and may contribute to fatigue, as stated in Sports Medicine 4
The National Institutes of Health suggests that magnesium and phosphate should be checked alongside vitamin D, as they work together in metabolic processes, as noted by Obesity Reviews 6, 7
The American Society for Nutrition recommends complete iron studies to detect early iron deficiency before anemia develops, as reported by Obesity Reviews and the Journal of the National Comprehensive Cancer Network 2, 5
The Academy of Nutrition and Dietetics advises testing zinc and copper together, as they affect each other's absorption, and selenium deficiency can contribute to fatigue and is often overlooked, as stated by Obesity Reviews 2, 3, 6

The Endocrine Society notes that patients on GLP-1/GIP agonists like tirzepatide may have altered nutrient absorption and significantly reduced food intake, increasing the risk of micronutrient deficiencies 2

The Journal of the Academy of Nutrition and Dietetics warns against assuming fatigue is solely due to caloric restriction, as vitamin deficiencies can contribute significantly to fatigue symptoms, as reported by the Journal of the National Comprehensive Cancer Network 5, 8
The American College of Nutrition advises against overlooking trace minerals, such as zinc, copper, and selenium, as deficiencies in these micronutrients can contribute to fatigue, as stated by Obesity Reviews 2, 3
The National Institutes of Health recommends assessing B vitamins together, rather than in isolation, due to their interrelationship, as noted by the Proceedings of the Nutrition Society 1
The Academy of Nutrition and Dietetics suggests assessing vitamin D status, even in non-bariatric weight loss, as vitamin D deficiency is common, as reported by Sports Medicine 4