Cholesterol Lab Test

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Latest Edit: Iva Lloyd, ND 2017-05-05 (EDT)

See Also Lab Tests

Cholesterol is a steroid, which is a waxy organic compound, that is found in every cell of the body and in the plasma. The presence of cholesterol is essential to life. Endogenous (internal) synthesis by the liver and other organs produces between 60-80% of the body's cholesterol. The remainder comes from exogenous (external) dietary sources.

Total cholesterol involves all of the cholesterol found in the body such as LDL cholesterol, HDL cholesterol, and triglycerides. The level of cholesterol in the body is primarily affected by metabolic rate. Generally speaking, increased levels are associated with thyroid or adrenal hypofunction, and decreased levels are associated with endocrine hyperfunction.


Cholesterol is vital to health as it:.[1], [2]

  • Controls membrane fluidity and is an essential component in the structure of the cell membrane.
  • Protects the vascular wall and attaches to it if it is damaged.
  • Is the structural backbone for every steroid hormone in the body, including adrenal and sex hormones and vitamin D.
  • Acts as a antioxidant to prevent free radical damage.
  • Helps form the myelin sheaths of nerve fibers and the bile salts that emulsify fats.

Patient Preparation

  • Patient must fast 12-14 hours after eating a low-fat meal before testing. Water is permitted.
  • Note: dietary intake for 2 weeks before testing will affect results. Therefore, patient should eat a normal diet for at least 1 week before testing.
  • No alcohol should be consumed 24 hours before the test.
  • Factors which can cause increased levels
  • Thiazide therapy, oophorectomy and postmenopausal status, levels tend to be higher in the fall and winter
  • Drugs: adrenocorticotropic hormone, anabolic steroids, beta-adrenergic blocking agents, coticosteroids, epinephrine, oral contraceptives, phenytoin (Dilantin), sulfonamides, cyclosporine, and Vitamin D
  • Factors which can cause decreased levels
  • values may decrease by as much as 10% when a patient changes from a standing to a recumbent position, major illnesses e.g. post MI, bacterial sepsis, and viral infections, high ascorbic acid levels, levels tend to be lower in the spring and summer
  • Drugs: allopurinol, androgens, bile salt-binding agents, captopril, chlorpropamide, clofibrate, colchicine, colestipol, erythromycin, isoniazid, liothyronine (Cytomel), lovastatin (Mevacor), monoamine, oxidase inhibitors, neomycin (oral), niacin, and nitrates

Clinical Implications

Ranges: The following are the reference ranges for this lab. However, lab ranges can vary by laboratory and country. [3]

Standard U.S. Units Standard International Units
Conventional Laboratory Range 130-200 mg/dL 3.36-5.2 mmol/L
Optimal Range 150-220 mg/dL 3.9-5.69 mmol/L
Alarm Ranges <50 or > 400 mg/dL <1.29 or > 10.34mmol/L

High levels indicate:

Low levels indicate:

Associated Tests


  1. Pagana Kathleen D, Pagana Timothy J (1998) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby, Inc
  2. Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain
  3. Weatherby Dicken., Ferguson Scott. Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain