…who have had any form of bariatric operation. This is not meant as a comprehensive interpretation of these particular analyses. For that, we would refer you to any one of a number of comprehensive clinical pathology or laboratory test books. We recommend these tests and other analyses that might come up from time to time on an annual basis for weight loss surgery patients. For the annual tests we list below, we recommend that bariatric patients stay off their vitamins and calcium for several days prior to them, and that these analyses be done in a fasting state.

CarnitineComplete blood count (CBC)
Comprehensive metabolic panel (CMP)Copper
FolateRBC folate level
IronTransferrin saturation
Fasting lipid panelLiver function panel
PTH, intactTSH
Vitamin AVitamin B6
Vitamin B12Serum methylmalonic acid
Serum homocysteine levelVitamin D, 125 hydroxy

Amylase is generally a blood test used to evaluate the pancreas when there is abdominal pain. While amylase is produced in the pancreas, it is also produced in the salivary glands. Some weight loss surgery patients may have chronic pancreatitis, in which case they may have a low level pain. A decreased value can indicate severe destruction of liver and pancreatic tissue or pancreatic insufficiency.

Calcium should be examined annually even though it is unlikely that you will find increased calcium levels in weight loss surgery patients. Usually increased ionized calcium values reflect an underlying primary hyperparathyroidism. Decreased levels are seen in vitamin D deficiency, magnesium depletion, secondary to diarrhea, or in celiac disease. A number of factors will interfere with calcium absorption, such as oxalates, citrates, alcohol, antiepileptic medicines, estro-gens, lithium, and thiazide diuretics. In distal gastric bypass patients (which include DS, BPD, and distal RNY), there is a fair bit of unabsorbed fat in the colon. This unabsorbed fat will bind with calcium, allowing oxylates to freely go back into the blood stream. The oxylates find their way back to the kidneys where they combine with calcium and form stones. Hence, keeping higher levels of calcium in the diet actually prevent stones—and you thought this would be a boring list of lab tests.


Carnitine is a co-factor in free fatty acids.Carnitine deficiency is found in diabetes, cardiomyopathy or other myopathies. Weight loss surgery patients with decreased levels are in danger of muscle degradation.

Beta-Carotene is a precursor to vitamin A.Carotenoids are a family of agents, some of which are precursors to vitamin A. Increased values are found in anorexia nervosa, diabetes, pregnancy, hypothyroidism, some liver disease, and high intake of vitamin A. Decreased values are found with celiac disease, low fat diets, malabsorption syndromes, or malnutrition.

Celiac Disease Antibody Profile: these tests include antigluten antibod-ies, endomysial antibodies, gliadin antibodies. Some weight loss surgery patients develop a celiac, disease which can be permanent or temporary. Given that one out of 133 people have this disease, it is worthwhile knowing what tests are available. This test is best ordered when a person is still taking gluten products, as it will normalize after TPN, or a gluten free diet.

Copper levels are another factor used to check nutrition. They are de-creased in celiac disease (again, this can be an issue in any bariatric patient who has had a bypass of any amount of small bowel) and in some malabsorption syndromes.

Ferritin levels are another marker for iron deficient anemia, and are one of a number of tests that might be ordered for this.

Iron can also be checked, as decreased levels can indicate inadequate iron absorption. While maximum iron absorption takes place in the duodenum and the upper jejunum, the remaining small bowel can increase absorption.

Magnesium levels can be decreased by chronic malabsorption, especially in weight loss operation patients who have had a jejuno-ileal bypass, those with celiac disease, Crohn’s disease, and others who have had part of their gut bypassed.

Parathyroid hormone are often checked, as increased levels indicate vitamin D deficiency, as well as hyperparathyroidism. This factor might also indicate that calcium levels are being maintained normally at the expense of the bone structure.

Prealbumin is synthesized by the liver and is decreased in weight loss surgery patients who have malnutrition. It is a protein with a fast turnover, and therefore gives a good nutritional status of the patient’s protein intake over the last few weeks.

Thyroid Stimulating Hormone is decreased in hyperthyroidism and in mal-nutrition, so test this test should be done in addition to the usual thyroid-axis tests. It is increased in weight loss operation patients with hypothyroidism secondary to decreased thyroid function.

Zinc is a trace metal and probably the second most important micronutrient. It is involved in wound healing, growth, and skin. It is found in high protein foods, such as meat, fish, and dairy products, and it is absorbed in the last part of the small bowel. It should not be an issue but often it is. Malnutrition and malabsorption can cause low zinc levels, and zinc again should not be taken for granted.