Solubility Information and Courses from MediaLab, Inc.

The heat and acetic acid test is another semiquantitative test used to confirm the presence of protein in urine. It is more sensitive than the SSA test because the pH of the sample is brought close to the isoelectric point of proteins. However, this test is sometimes considered too sensitive because it can detect trace amounts of protein which are considered normal. The heat and acetic acid test gives false positive results with inorganic iodides, benzoin, tolutamide, and proteoses, similar to the SSA test. Bence-Jones protein consists of dimers of either kappa or lambda light chains from immunoglobulins. This abnormal protein is most often associated with multiple myeloma, but can also be found in cases of lymphoma, macroglobulinemia, leukemia, and other malignancies (Balant and Fabre, 1978). Testing for Bence-Jones protein is not part of the routine urinalysis. However, if Bence-Jones protein is suspected, the heat precipitation test or immunoelectrophoresis can be performed on a urine specimen. The heat precipitation test is based on the protein’s unusual solubility properties. Bence-Jones protein precipitates at temperatures between 40ºC and 60ºC (56ºC optimum), but dissolves again at 100ºC. Upon cooling, the precipitate will reappear around 60ºC and will dissolve again below 40ºC

Physical and chemical characteristics of the chemical include: Boiling point Specific gravity Solubility Appearance Odor

In addition to protein availability, other factors may affect drug absorption and distribution in the body as a whole or at specific sites within the body. The following table highlights some of these other factors. Factor Discussion Regional blood flow Reduced area blood flow can be seen in diabetics and enhanced blood flow can be seen in tumors. Lipid solubility of the drug The more lipophilic a drug is, the more likely it will enter the central nervous system. The integrity of the GI tract In a diseased gut, an orally-administered drug may not be absorbed as expected. Age Drug kinetics and dispositions change throughout life. In general, metabolism of drugs is reduced in the elderly. Genetics Mutations or deletions in drug metabolizing enzymes can greatly affect a drug's disposition.

Identification of crystals found in the urine sediment requires knowledge of the urinary pH. Large crystals are identifiable under low power. High power magnification is required for smaller crystals. Most crystals can be identified by morphology alone. Urine pH and reagent strip results can provide supporting information. If further examination is necessary birefringence and solubility characteristics should be performed.