question: How to diagnose High blood cholesterol levels?: A cholesterol test is done to diagnose a lipid disorder. Some guidelines recommend having your first screening cholesterol test at age 20. Everyone should have their first screening test by age 35 in men, and age 45 in women. (Note: Different experts recommend different starting ages.)  It is important to work with your health care provider to set your cholesterol goals. Newer guidelines steer doctors away from targeting specific levels of cholesterol. Instead, it recommends different medicines and doses depending on a person's history and risk factor profile.  General targets are:  - LDL: 70 to 130 mg/dL (lower numbers are better)  - HDL: more than 50 mg/dL (high numbers are better)  - Total cholesterol: less than 200 mg/dL (lower numbers are better)  - Triglycerides: 10 to 150 mg/dL (lower numbers are better)     If your cholesterol results are abnormal, you may also have other tests such as:   - Blood sugar (glucose) test to look for diabetes  - Kidney function tests  - Thyroid function tests to look for an underactive thyroid gland