Guide to understanding and interpreting your blood test results during tirzepatide treatment: blood glucose, lipids, liver, kidneys, and deficiencies.
Glycemic markers
Under tirzepatide, glycemic markers show favorable changes. Fasting blood glucose (normal: 0.70 to 1.10 g/L) decreases thanks to the drug’s action on insulin secretion and insulin sensitivity. HbA1c (glycated hemoglobin), which reflects average blood glucose over 3 months, significantly improves: the SURMOUNT-2 trial showed an average reduction of 2.1% in diabetic patients.
For non-diabetic patients, these markers serve for monitoring. A fasting blood glucose below 0.60 g/L or an HbA1c below 4.5% may indicate a risk of hypoglycemia, especially in cases of prolonged fasting or intense exercise. Report these values to your doctor. The improvement in insulin resistance is one of the major benefits of tirzepatide, even in non-diabetic individuals.
The lipid profile
Tirzepatide significantly improves the lipid profile. Expected results include a decrease in total cholesterol and LDL-cholesterol (the “bad” cholesterol), a reduction in triglycerides (often dramatic, -25 to -35% in trials), and a modest increase in HDL-cholesterol (the “good” cholesterol). An LDL below 1.30 g/L is the standard target; in cases of high cardiovascular risk, the target may be below 0.70 g/L.
Liver function test
The liver function test (AST, ALT, GGT, alkaline phosphatase) monitors liver function. Tirzepatide has demonstrated a beneficial effect on hepatic steatosis (NASH), with a reduction in liver fat documented by imaging in clinical trials. However, a transient elevation of transaminases (AST, ALT) beyond 3 times the upper normal limit requires a thorough evaluation and potentially a treatment adjustment.
Renal function and thyroid
Creatinine and glomerular filtration rate (GFR) evaluate renal function. Tirzepatide is generally well tolerated renally, but dehydration (linked to nausea, vomiting, or insufficient fluid intake) can temporarily alter renal function. TSH monitors thyroid function, as GLP-1 agonists carry a theoretical warning about medullary thyroid carcinoma (observed only in rodents).
Nutritional deficiencies to monitor
- Ferritin and transferrin saturation (iron deficiency)
- Vitamin D (common deficiency, aggravated by rapid weight loss)
- Vitamin B12 (possible deficiency if significant reduction in protein intake)
- Folates (folic acid), especially in women of childbearing age
- Calcemia and phosphoremia (bone metabolism)
- Albumin and pre-albumin (overall nutritional status)
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FAQ
What blood test results should be monitored on tirzepatide?
Essential markers include blood glucose/HbA1c, lipid panel, liver function test, renal function, CBC, ferritin, vitamins D and B12, and TSH. Your doctor will adapt the analyses according to your comorbidities.
Does tirzepatide improve cholesterol?
Yes, clinical trials show a significant improvement in the lipid profile: a decrease in LDL-cholesterol, a 25-35% reduction in triglycerides, and a modest increase in HDL-cholesterol. These effects are a major benefit of the treatment.
How often should blood tests be done on Mounjaro?
Blood tests are recommended every 3 to 6 months during treatment. During the active titration phase, a quarterly test is preferable. In the maintenance phase, a semi-annual test may suffice if previous results are normal.
Should one worry about elevated transaminases?
A modest and transient elevation of transaminases is possible and often benign. However, an elevation greater than 3 times the normal limit requires a thorough evaluation. Tirzepatide generally improves hepatic steatosis in the medium term.