Terminology
Renal System - the kidneys and urine formation and urination; synonymous with Urinary System
Urinary System - synonymous with Renal System
Genitourinary System - genitals (male, female) and urinary system
Renal System
The kidneys, ureters, urinary bladder and urethra form the renal system.
https://en.wikipedia.org/wiki/Urinary_system
Renal Profile
Also known as Renal Panel.
https://labtestsonline.org/understanding/analytes/renal-panel/tab/sample/
Renal Function
The Renal Function comprises tests that indicate the status of the kidneys. The kidneys have several functions.
Renal Function Tests (RFT)
Renal Function Tests (RFT) are a set of biochemical tests that determines the status of the kidneys.
Renal Section
Clinical laboratories have a separate section that handles urine specimens and their manual testing. It is called the Renal Section. It is also the smelliest section of any clinical lab if the urine samples are not disposed immediately after analysis or if the fumehood is not functioning properly.
Urinalysis
Urinalysis refers to the biochemical analysis of urine. It includes several tests, manual and automated.
Urine Dipstick Test
A urine dipstick test is a simple means to determine certain chemical contents of urine (less the 5 minutes) using a dipstick. A dipstick is a plastic strip with many little patches or test pads. The dipstick is dipped in urine and excess urine is removed. The dipstick is left for a few minutes to let the colour reaction of the various pads to develop. The coloured test pads are then checked against the printed values on the cans the dipstick came in.
The urine dipstick test is demonstrated in class practicals and often appear in professional examinations. Students test 2 urine samples and are required to record the dipstick test values within 3-5 minutes.
The urine dipstick tests for Specific Gravity (SG) of urine, presence of glucose, protein, etc.
Not all urine tests can be done using the urine dipstick.
Many renal function tests are performed by automated chemistry analysers, using commercially available kits. These set of tests are known as Renal Function Tests (RFT) or Renal Profile.
Specific Gravity (SG)
https://en.wikipedia.org/wiki/Urine_specific_gravity
(i) High Urine SG
Hypersthenuria is urine with high SG, due to increased concentration of solutes in the urine. It occurs in dehydration, diarrhoea, emesis, excessive sweating, urinary tract/bladder infection, glucosuria, renal artery stenosis, hepatorenal syndrome, decreased blood flow to the kidney (especially as a result of heart failure), and excess of antidiuretic hormone caused by Syndrome of inappropriate antidiuretic hormone.
- Frank dehydration SG >1.035
- Neonates SG = 1.003
- Hypovolemia SG >1.015
(ii) Low Urine SG
Hyposthenuria is urine with low SG due to decreased concentration of solutes in urine. It occurs in renal failure, pyelonephritis,diabetes insipidus, acute tubular necrosis, interstitial nephritis, and excessive fluid intake (e.g., psychogenic polydipsia).
Osmolality
This is the amount of all dissolved solutes in urine. It is measured using a semi-automated osmometer, that uses freezing-point depression for determination of solutes, which is then correlated with osmolality. An example of an osmometer is the Gonotec Osmomat. Approximately 200 microlitres of urine is required for this test, which is placed in a thin-wall micro Eppendorf tube. It takes a few minutes to determine urine osmolality. Urine osmolality is expressed as milliosmoles/kg (mOsm/kg).
In healthy people, when osmolality in the blood becomes high, the body releases antidiuretic hormone (ADH). ADH causes the kidneys to reabsorb water, which results in more concentrated urine. The reabsorbed water dilutes the blood, and returns blood osmolality to normal.
Low blood osmolality suppresses ADH, and reduces the amount of water that the kidneys reabsorb. Blood osmolality increases towards normal. Dilute urine is passed to get rid of the excess water.
In healthy people, when osmolality in the blood becomes high, the body releases antidiuretic hormone (ADH). ADH causes the kidneys to reabsorb water, which results in more concentrated urine. The reabsorbed water dilutes the blood, and returns blood osmolality to normal.
Low blood osmolality suppresses ADH, and reduces the amount of water that the kidneys reabsorb. Blood osmolality increases towards normal. Dilute urine is passed to get rid of the excess water.
Creatinine
Creatinine is a waste product from muscle degradation (breakdown), from creatine. The more muscle is degraded (broken down), the higher the creatinine value in blood. Creatinine is cleared from blood by the kidneys. Healthy kidneys help to maintain creatinine at constant normal levels in the blood. However, during dehydration (during hot weather or reduced water intake), blood creatinine is elevated. Elevated creatinine can also indicate kidney failure or disease, as the kidneys cannot clear creatinine and creatinine levels thus build up in blood.
Creatinine clearance
The kidneys clear creatinine from blood. Blood creatinine is filtered and cleared, and appears as urine creatinine. Measuring the clearance of creatinine from the blood is a biochemical test of kidney function. Poor creatinine clearance means the kidneys cannot clear creatinine fast enough from the blood.
Ammonia
Most ammonia in the body forms when protein is broken down by bacteria in the intestines. The liver normally converts nitrogenous chemicals in the body (eg proteins) as ammonia. The liver too converts ammonia into urea.
The normal liver removes the ammonium ions from proteins. These ammonium ions form urea via the urea cycle.
(a) Urea cycle and elimination of ammonia as urea
The human body has a specific mechanism to prevent the build-up of ammonia in the bloodstream. Ammonia is converted to carbamoyl phosphate by the enzyme carbamoyl phosphate synthetase, and then enters the urea cycle to be either incorporated into amino acids or excreted in the urine.
Ammonia is excreted from the body as urea, which is eliminated in urine.
(b) Dietary effects of ammonia and urea
A high protein diet may lead to high ammonia levels in blood and high blood urea.
(c) Acidosis
In acid-base balance, the kidneys secrete ammonia to neutralize excess acid.
(d) Liver failure and ammonia toxicity
In liver failure, blood ammonium levels can rise and lead to ammonia toxicity, which affects the brain. This is critical in newborn babies who do not have a normal liver or normal liver enzymes.
Ammonia levels in the blood rise when the liver is unable to convert ammonia to urea. This may be caused by cirrhosis or severe hepatitis.
High levels of ammonia in the blood may be caused by:
- Liver disease, such as cirrhosis or hepatitis
- Reye syndrome
- Heart failure
- Kidney failure
- Severe bleeding from the stomach or intestines.
An ammonia test measures the amount of ammonia in the blood.
Blood ammonia values:
Adults 7–35 micromoles per liter (mcmol/L)
Adults 7–35 micromoles per liter (mcmol/L)
Children 28–57 mcmol/L
Newborns 64–107 mcmol/L
(f) Precautions
(f) Precautions
WARNING: Never mix ammonia with bleach (eg Clorox). This causes the release of toxic chlorine gas, which can be deadly.
Ammonia concentration and toxicity:
Household ammonia is a solution of NH3 in water (i.e., ammonium hydroxide). It is used as a general purpose cleaner for many surfaces. Because ammonia results in a relatively streak-free shine, one of its most common uses is to clean glass, porcelain and stainless steel. It is also frequently used for cleaning ovens and soaking items to loosen baked-on grime. Household ammonia ranges in concentration by weight from 5 to 10% ammonia.
Solubility of ammonia in water is 31% w/w (25 °C)
The toxicity of ammonia solutions does not usually cause problems for humans and other mammals.
Urea
Urea is a waste product which is excreted in urine. Urea is less toxic compared to ammonia, its precursor.
Worker safety:
Urea
Urea is a waste product which is excreted in urine. Urea is less toxic compared to ammonia, its precursor.
External links
http://www.medicinenet.com/kidney_stone_pictures_slideshow/article.htm
http://www.stylecraze.com/articles/serious-side-effects-of-lemon/?ref=ka
http://www.nlm.nih.gov/medlineplus/ency/article/003463.htm
http://www.webmd.com/digestive-disorders/ammonia-test
https://en.wikipedia.org/wiki/Ammonia
http://www.pilotfriend.com/aeromed/medical/kidney.htm
http://www.stylecraze.com/articles/serious-side-effects-of-lemon/?ref=ka
http://www.nlm.nih.gov/medlineplus/ency/article/003463.htm
http://www.webmd.com/digestive-disorders/ammonia-test
https://en.wikipedia.org/wiki/Ammonia
http://www.pilotfriend.com/aeromed/medical/kidney.htm
