Urine Analysis and Laboratory Tests

The data of Urine analysis usually taken are divided into two; qualitative and quantitative data of Urine laboratory tests. As their names imply, qualitative tests is to test for the qualities of the Urine such as colour, transparency, etc, while quantitative test, try to find the amounts of some indexes in the Urine such as volume, specific gravity, amount of pathologic components of Urine (blood, proteins, creatinine, etc).

Qualitative data of Urine laboratory tests

Colour of Urine

• In the first day of child’s Life, Urine is colorless

• On the 2nd-4th days- dark-reddish, because big quantity of Urea is excreted.

• In breast fed infants the urine is almost colorless until they start to drink fruit juices and to eat other foods at the age of 4-6 months

• In formula fed infants, all children and grown-ups, the urine is yellow like straw.

Changes of Urine color can be physiological. For example;

• Colorless urine is excreted when a person drinks a lot of fluids

• Urine acquires Orange color when the food contains a lot of carotene (carrot);

• Urine will be pink after eating red-beet;

• Some medicines influence the Urine colour. SO, rifampicin causes the red color of Urine, analginum and sulfacylamides-pink, mitroxolinum-saffron-yellow.

Some Urine discoloration is of diagnostic value in case of Kidney disorders:

• Dark-brown Urine is a pathognomic symptom of virus hepatitis; the cause of such color is big amount of bile pigments hyperbilirubinuria); characteristic sign is forming of yellowish foam after shaking such Urine.

• Smoky brown Urine, which resembles tea or cola, is formed in case of nephron damage, when RBCs pass through the basal membrane of glomerular capsule and losses the hemoglobin. It is the main sign of acute poststreptococcal glomerulonephritis

• Bright red color can be found when “fresh” RBCs pass into urine in case of trauma, kidney tuberculosis, crystals, cystitis, urethritis, renal tumor.

• Dark-violet discoloration is the sign of considerable RBCs hemolysis in case of poisoning, Rh-conflict, mistakes during blood transfusion etc.

Transparence

The Urine can be cloudy only in newborn child for 2-3 days after birth. After that each healthy person excrete transparent Urine. Cloudy hazy, darkly opalescent Urine can be found in case of Urinary tract infection, enlarged amount of crystals, RBCs or WBCs, pus or fats in Urine.

Quantitative data of Urine Laboratory tests

Diuresis means the process of Urine production. The Urine-volume (UV per 24 hours) is its laboratory reflection. Its meanings depend on age.

Pathological changes of Urine volume

• Poliuria is diagnosed when the urine volume exceeds the normal ranges in 2 times and more. It is the often sign of disorders with other systems decreasing of cardiac edema, diabetes mellitus, diabetes insipiduc). Renal poliutia develops in case of back progress of nephritic edema, chronic renal failure.

• Oliguria means the decreasing of daily urine volume to of age ranges and less. Renal Oliguria is one of the most significant manifestations of renal failure. There also can be extra-renal causes of Oliguria such as massive profuse bleeding, diarrhea, poisoning, cardiax failure, shock. It is very important to identify the reason of Oliguria because the therapeutic plans can be quite different when the Urine volume decrease less than 5% of normal data or there is no Urine per whole day. It is one of the most dangerous conditions for the child’s life and needs the emergency medical help.

• Anuria can be

1. renal-the kidneys don’t form the urine due to considerable damage of their tissues.

2. postrenal (mechanical)-the Urine is produced, but it doesn’t go into the bladder because of upper tract or bladder neck obstruction.

• Nocturia, the normal correlation of daytime and nighttime Urine Volume is 2:1. That means that because of bigger fluid intake and physical activity, Urine excretion is more intensive during daytime. If the night Urine volume is bigger, it is the manifestation of decreased renal function.

Ph of Urine

This sign depends on age, food habits, prescribed medicines and differs in different people as well as in one person in different periods.

Specific gravity

It is the concentration of electrolytes and other substances dissolve in Urine. Decreasing of specific gravity can be seen in case of drinking a lot of fluids, severe renal failure, back progress of edema, diabetes insipidus. Increasing is observed at Oliguria, diabetes mellitus, excretion of marked amount of protein. Excretion of 0.1g of glucose per 11 of Urine causes enlargement of specific gravity on 0.004; 0.4 of protein-on 0.001.

Indexes of Urine analysis which are deviations of the normal ones are indications for metabolic disorders