The Urine Glucose Test.
Also known as Urine sugar or Glucosuria Test.
As is obvious from it’s name this test measures the amount of glucose in the urine.
Though this test used to be the norm, and in fact the only way for diabetics to keep a check on their glucose levels it has been largely replaced with self-monitoring of blood glucose using a blood glucose meter.
When is this test done?
It is used as a quick screen for possible diabetes in the doctor’s surgery. As a home test it is now only done by those people who are unable to use a blood glucose meter or in third world countries where there are no funds available for meters and strips. Dipsticks are much cheaper and are often be cut lengthways to make them last even longer.
Two of the most oft used brands are Clinitest, Clinistix & Tes-tape.
Preparing for test.
You need no special preparation except to abstain from taking any drugs that may interfere with the test results.
How the test is done.
A urine sample is taken and the glucose is measured using a dipstick. This is a thin strip of plastic with a pad at the one end that is impregnated with specific chemicals. These chemicals with glucose and change colour depending on the amount of glucose present. The results are then read by comparing the dipstick to a supplied colour chart.
Normal Values - no glucose detectable in urine.
Abnormal results - glucose detected in the urine sample means -
1. Diabetes mellitus
2. Renal glycosuria. This is a kidney disease where glucose leaks into the urine even when blood glucose levels are normal. It can occur on it’s own or as part of other kidney diseases like Fanconi's Syndrome.
There are unfortunatly major drawbacks in this type of testing.
1. Glucose only shows up in the urine once it has reached high levels in your blood.
Anything below 10mmol/L (180 mg/dl) will not show up so besides it’s uselessness for detecting hypos, all it will tell you is that your control is not working.
2. Exact readings are impossible as the colour coding is just an indication of what range your BG’s are - so you may know ‘okay, low, high, very high’ but this is a tad vague, especially if you are looking for tight control. Even 'okay' only shows that your blood glucose is below 10mmol/L (180 mg/dl)
3. Urine glucose does not give you any indication of how a particular substance affects your glucose levels at the time of consuming it.
What may influence the results.
Drugs that may cause an increase in urinary glucose are:-
1. Aminosalicylic acid - an antibiotic mainly used to treat tuberculosis.
2. Cephalosporins - antibiotics used to treat a wide variety of infections, particularly those of the respiratory, skin and urinarys.
3. Chloral hydrate - used as a sleeping aid for insomnia.
4. Chloramphenicol - an antibiotic used in the treatment of infections.
5. Dextrothyroxine - a blood thinner.
6. Diazoxide - used in the treatment of hypoglycemia
7. Diuretics (loop and thiazides) - "water pills" used to reduce fluid accumulation in the body by increasing urination.
8. Estrogens - relief of moderate to severe hot flashes and other symptoms of oestrogen deficiency.
9. Isoniazid - antibiotic used to prevent and treat tuberculosis.
10. Levodopa - used to treat symptoms of Parkinson's disease.
11. Lithium - used for the treatment of bipolar and depressive disorders.
12. Nafcillin - an antibiotic.
13. Nalidixic acid - an antibiotic used to treat urinary tract infections.
14. Nicotinic acid (large doses) - used to reduce cholesterol and triglyceride levels in the blood.
False positive results have been known to show up when using Clinitest dipsticks (but not with Clinistix or Tes-tape) if you are taking:-
1. Acetylsalicylic acid - aspirin.
2. Aminosalicylic acid - antibiotic
3. Ascorbic acid - vitamin C
4. Cephalothin - antibiotic
5. Chloral hydrate - sleeping aid
6. Nitrofurantoin - antibiotic
7. Streptomycin - antibiotic
8. Sulfonamides - antibiotics
False negatives are given by:-
1. Ascorbic acid - if using Clinistix or Tes-tape
2. Phenothiazines - if using Clinistix or Tes-tape (This medication is used to treat mental/emotional conditions. It is also used to treat nausea and vomiting)
3. Levodopa - using Clinistix