It is a clear, colorless fluid formed in the ventricles of the brain mainly by choroid plexus (an interlaced structure or meshwork of tiny small blood vessels in the lateral third and fourth ventricles). It is mainly an ultrafiltrate of plasma.

Collection of sample This test is performed with the patient's serum. There is no restriction for a fasting sample. The test can be done by a random blood sample the patient. About 3 to 5 ml of blood is collected in a plain test tube, and blood is allowed to clot to get clear serum. In infants, the sample may…

Total serum thyroxine includes both free and protein-bound thyroxine and is usually measured by competitive immunoassay. Normal level in adults is 5.0-12.0 μg/dl.   Test for total thyroxine or free thyroxine is usually combined with TSH measurement and together they give the best assessment of thyroid function.   Causes of Increased Total T4   Hyperthyroidism: Elevation of both T4 and…

Two biochemical parameters are commonly used to assess renal function: blood urea nitrogen (BUN) and serum creatinine. Although convenient, they are insensitive markers of glomerular function.   Blood Urea Nitrogen (BUN)   Urea is produced in the liver from amino acids (ingested or tissue-derived). Amino acids are utilized to produce energy, synthesize proteins, and are catabolized to ammonia. Urea is…

Glomerular filtration rate refers to the rate in ml/min at which a substance is cleared from the circulation by the glomeruli. The ability of the glomeruli to filter a substance from the blood is assessed by clearance studies. If a substance is not bound to protein in plasma, is completely filtered by the glomeruli, and is neither secreted nor reabsorbed…

Diabetes mellitus (DM) is a metabolic group of disorders characterized by persistent hyperglycemia due to deficiency and/or diminished effectiveness of insulin. There are derangements of carbohydrate, protein, and fat metabolism due to failure of insulin action on target cells.