7.2 Physical Examination of Urine
7.2.1 Color and Odor
Normal urine is colorless to straw colored due to presence of urochrome. Slight
change in color occurs in fever, dehydration jaundice, or vitamin B-complex therapy
which adds riboflavin (deep yellow color). Red to brown color is observed in
hematuria, hemoglobinuria, myoglobinuria, and porphyria. Urine turns brown to
black in alkaptonuria and methemoglobinuria. Normally odor of urine is faintly
aromatic. On decomposition, a very unpleasant ammoniacal odor evolves. Food
beverages and drugs may impart a specific odor to urine.
7.2.2 Appearance
Normally freshly voided urine is clear and transparent, but it may become turbid if
exposed for a long time due to the bacterial action on urea present in urine to convert
it into ammonium carbonate. Phosphate excretion in alkaline urine also makes urine
turbid. The presence of white cells, red cells, or epithelial cells makes urine cloudy.
Fat globules give urine milky appearance.
7.2.3 Specific Gravity
Specific gravity of urine is measured by urinometer. Specific gravity of normal urine
is between 1.002 and 1.026 and depends upon state of hydration, diet,fluid intake,
drugs, etc. Severe dehydration, diabetes mellitus, adrenal insufficiency, diabetes
insipidus, and chronic nephritis increase specific gravity (Fig.7.1).
7.2.4 Volume
Normal healthy individual excretes about 800–2000 ml of urine/day. Daily urinary
excretion depends upon intake offluid volume, loss offluid, solute load, climatic
condition, fever, or intake of drugs. The term polyuria is used if urinary output is
more than 3000 ml/day. It occurs in conditions like diabetes insipidus, diabetes
mellitus, or recovery from acute renal failure. In oliguria, urine output is less than
500 ml/day. Oliguria may be due to fewer intakes of water or due to dehydration or
may indicate early renal dysfunction symptoms. In anuria, a complete cessation of
urine output (<100 ml/day) is observed. Anuria should be taken care immediately;
otherwise complete renal failure may take place.
30 7 Examination of Urine for Normal Constituents