A question arises in mind with an exclamation mark, can a simple test like Urinalysis or UA is really capable of telling us about renal diseases or what is wrong happening in our body!
The answer is yes. It is a simple yet quite informative test especially in assessing renal functions and additionally it may give us some more information.But what is Urinalysis? UA is actually in very simple terms the Analysis Of Urine.Now we would be discussing UA step by step so that we may know how does this test helps us in gaining some important information about our renal functions:
1-Color of Urine
Normal: Ranges from colorless to deep yellow depending on the concentration of the urochrome pigment.
Red: Indicates hemoglobinuria, myoglobinuria or hematuria (blood in urine)
Orange: This color happens if a person is taking rifampicin (This drug is taken by patients who are suffering from Tuberculosis or TB)
Yellow: Indicates concentrated urine which usually occurs in dehydration, jaundice, and with the use of sulfasalazine and Vitamin B Complex)
Green: Methylene Blue (This is a blue dye and is found as a component in several medicines)
Black: Happens in severe hemoglobinuria and in case of use of methyldopa.
Brown: Indicates bilirubin and also happens with use of phenothiazines.
2-Volume of Urine
Normal volume of urine is 800-2500 ml/day. In case of Oliguria, urine volume is less than 300 ml/day. And in Anuria, urine volume is less than 100 ml/day. It is very important to note that complete anuria suggests either an acute vascular event or total urinary obstruction; even in the most severe intrinsic renal disorders some urine is usually still produced. Polyuria, which refers to the production of an excess volume of urine, may have a number of causes like:
Excess fluid intake Osmotic, e.g. hyperglycemia Cranial diabetes insipidus (loss of antidiuretic hormone-ADH) Nephrogenic diabetes insipidus (NDI) (tubular dysfunction)
-Genetic tubular cell defects: ADH receptor, aquarian mutations
-Drugs/Toxins: lithium, diuretics, hypercalcemia, Interstitial renal disease
3-Specific Gravity of Urine
It varies with the quantity of urine. Its normal range is 1.002 to 1.025. Estimation is required in investigation of polyuria or SIADH (Syndrome of Inappropriate Antidiuretic Hormone Hypersecretion). Persistently low specific gravity suggests chronic renal failure or diabetes insipidus while high specific gravity suggests dehydration or diabetes mellitus with presence of large amount of glucose in the urine.
4-Reaction of Urine
Fresh urine is acidic with an average pH of 6.The pH is important in investigation and management of renal tubular acidosis. Distal tubular acidosis should be suspected if the early morning urine is consistently alkaline and cannot be acidified.
Infection with urea-splitting microorganism Proteus mirabilis can cause urine alkaline that favors renal calcium stone formation.
Glucose in urine usually indicates diabetes but it may occur in impaired renal tubular ability to absorb glucose (renal glycosuria) such as in Fanconi's syndrome. False positive or negative results may occur if patient is taking large doses of Vitamin C or taking tetracyclines or levodopa.
Ketone in the urine of diabetic patient is an important indication of diabetic ketoacidosis. Ketones may be present in urine due to starvation also.
Normal protein loss from urine is less than 150 mg/24 hours. Causes of proteinuria are as following:
Primary renal diseases
Different types of glomerulonephriti
Secondary renal diseases
Systemic diseases: diabetes, hypertension and amyloidosis Drugs: captopril, penicillamine, heroine and NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) Infections: Hepatitis B, Infective Endocarditis, Malaria and AIDS Allergy: Vaccine and bee sting
1-White Blood Cells (WBCs)
More than 10 or more WBCs (White Blood Cells) per cm indicate Urinary Tract Infection or UTI (mostly) but it may also present in patients with stones, tubulointerstitial nephritis, tuberculosis and papillary necrosis.
2-Red Blood Cells (RBCs)
Presence of 2-5 RBCs per high power field (of microscope) indicates positive test for hematuria and can be detected on dipstick. Red cells may come from glomeruli or below. RBCs of glomeruli origin tend to be dysmorphic and have many sizes and shapes whereas RBCs of non-glomeruli origin are uniform in size and shape.
Theses are cylindrical structures that form within the kidney tubules by the coagulation of proteins. Their various types are discussed below:
Hyaline Cast: These are present in concentrated urine, in fever, after exercise and after diuretic therapy. Granular Cast: Theses are found in chronic glomerulitis, diabetic nephropathy and malignant hypertension. White Blood Cell Cast: These are found in acute pyelonephritis. Red Blood Cell Cast: These are found in acute tubular necrosis and interstitial nephritis. Broad Waxy Cast: These are found in chronic renal failure.
Various crystals may be found during microscopy.Their various types are mentioned below:
Uric Acid Crystals: Found in acidic urine, hyperuricosuria and in acute uric acid nephropathy Calcium Phosphate Crystals: Found in alkaline urine Calcium Oxalate Crystals: Found in hyperoxaluria and in acidic urine. Cystine Crystals: Found in cystinuria
So, in the end, we can conclude easily that Urinalysis, despite being a simple test provides us ample information not only about the renal diseases but may also pinpoint some other diseases like diabetes mellitus and malignant hypertension.