- Electrolyte levels. Electrolytes are minerals, such as potassium, calcium, and sodium. A severe imbalance of electrolytes can lead to seizures, an irregular heartbeat, muscle weakness, and other problems.
- Levels of iron, sugar, protein, and fat.
- The function of the kidneys, liver, and thyroid gland.
- Levels of certain hormones, such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in women and testosterone in men.
- Levels of vitamins and minerals in the body.
A doctor may also test whether you have difficulty digesting certain foods, such as milk and dairy products.