![]() The urine concentration of urea or creatinine is also determined. The 24-hour urine collection is the most commonly performed interval. Urine is collected for a fixed period ranging from 6, 12, to 24 hours. As in extrinsic clearance tests, the plasma levels of creatinine or urea are determined. Very little creatinine is secreted by the tubular cells therefore, the concentration of creatinine in urine is an excellent assessment of the tubular excretion function and the GFR. Creatinine is a waste product of muscle metabolism and is produced at a constant rate and proportional to muscle mass. Because approximately 40% of urea is reabsorbed into the tubules, the urea clearance test does not provide a full clearance assessment. The urea clearance test was one of the first clearance tests performed. Intrinsic clearance tests measure chemicals that are intrinsic to the body, such as creatinine and urea. After the time interval, which may be 6, 12, or 24 hours, the urine and plasma are analyzed for the chemical concentration. All urine is collected during the clearance procedure and the volume measured. ![]() After the chemical is injected, the plasma concentration is measured. The chemical is injected into the patient intravenously. These chemicals include inulin and p-aminohippurate, among others. Measurements of chemicals that are foreign to the body and completely cleared are known as extrinsic clearance tests. The clearance tests differ from one another by the chemical to be cleared by the kidney and analyzed. This is the rate at which chemicals are filtered or “cleared” from the kidney. In this manner, the glomerular filtration rate (GFR) can be determined. All of them measure three parameters: the plasma (or serum) concentration of the chemical to be cleared, the urine concentration of that same chemical, and the time interval of the clearance procedure. There are many variations on the clearance test. By measuring the concentration per unit of time in urine of a chemical that will be removed or “cleared” by the kidney tubules, the physiologic function of the tubules can be determined. The kidney’s main function is to excrete waste products while reabsorbing water and dissolved chemicals from the ultrafiltrate. This test provides information on the glomerular and tubular function of the kidneys. Results of all analytes will be reported, and the provider should decide if recollection is needed.One of the most common renal function tests is the clearance test. ![]() For midstream urine collection instructions refer to Health Facts for you:Ī comment will indicate high levels of SEC. Clean catch (midstream) urine collection may reduce the possibility of contamination. SEC may indicate the possibility of other contaminants such as bacteria. **** Squamous Epithelial Cells (SEC), present in a urine specimen likely enter from sites distal to the bladder. The presence of bacteria is not necessarily indicative of urinary tract infections. Higher levels will be reported as PRESENT or MANY. *** If bacteria are undetected or present at very low levels, bacteria will be reported as NEGATIVE. Included in non-ionic solutes are urea, glucose, and protein. Included in ionic solutes are sodium, chloride, sulfate, phosphate, and ammonium. The refractometer method includes both ionic and non-ionic solutes. For both ionic and nonionic solutes order “Specific Gravity, Urine”.The refractometer method is routinely included in urinalysis performed at the UH and TAC Laboratories and is the method used when "SPECIFIC GRAVITY, URINE" is ordered. If a specific gravity is performed via colorimetric test strip, the following comment will appear: Only ionic solutes measured. * All UW Health Laboratories may use a screening method for specific gravity, based on a colorimetric test strips which reports only the ionic solutes. None Seen or Present calcium oxalate Present amorphous urates or phosphates Samples held at room temperature for more than 2 hours or samples refrigerated for more than 24 hours are not acceptable. ![]() Transport with coolant pack if coming from clinic location. For example, the density of water at 60 degrees F is 1.000 g/cm3. There are no units of measure associated with it because it is a comparison. Transport specimen to the laboratory immediately. Specific gravity is the ratio of the density of a liquid compared to the density of water at 60 degrees F. For midstream urine collection instructions refer to Health Facts for you - Male HF #4247, Female HF # 4236 located on UConnect. Indicate whether specimen is midstream, indwelling catheter, single catheter or other method of collection. Refrigerate if transportation to lab is delayed. Urinalysis | Urinalysis with Microscopy UWHC Lab Test DetailsĪutomated Urine Chemistry and Microscopy Analyzerįirst morning void preferred.
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