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• Physical examination of urine is done after checking the request and only includes color and clarity
• Other parameters like odor and viscosity can be useful but are not included in reported results
• Urine color is a rough indicator of the state or degree of hydration and should be correlated with urine specific gravity (SG) due to its concentration
• Specific gravity (SG) in urine includes dissolved substances (or solutes) like sediments, WBCs, RBCs, casts, and crystals
• Darker urine color indicates increased specific gravity, while lighter color indicates lower specific gravity
• Normal urine color ranges from colorless to deep yellow, while abnormal colors include red or red-brown, which is the most common abnormal color
• Violet urine can indicate a bacterial infection caused by Chromobacterium violaceum producing a violet pigment called violacein
• Metabolic abnormalities, like inborn errors of metabolism (IEM), can also cause urine color variations
• Ingested food or drugs, such as multivitamins or TB drugs, are common reasons for changes in urine color
• Urochrome is a major urinary pigment contributing to normal urine color and is increased in conditions like thyrotoxicosis, fever, and starvation
• Uroerythrin, an orange-pink pigment, may deposit in urinary crystals after refrigeration and is a normal urinary constituent
• Urobilin imparts an orange-brown color to urine that is not fresh and is a normal urinary constituent
• Substances in urine can impart different colors depending on the amount present, urine pH, and structural form of the substance
• Urine color variations can indicate different causes like recent fluid consumption, dehydration, pathologic conditions like jaundice, infections, and metabolic abnormalities
• Different colors in urine, like green, pink-red, brown-black, and others, can indicate various pathologies or conditions
• Hematuria, hemoglobinuria, and myoglobinuria have distinct characteristics in terms of color, clarity, microscopic examination, and chemical examination
• Hemoglobinuria and myoglobinuria can be differentiated using tests like the ammonium sulfate test, plasma color, and specific enzyme levels
• Ferritin is denatured by renal cells in the proximal convoluted tubule (PCT) to form hemosiderin, which is found in urine
• Hemosiderin granules in urine indicate hemoglobinuria
• Hemosiderin may be mistaken for bilirubin crystals as both have a yellowish appearance under the microscope; use Prussian blue stain to differentiate
• To test for hemoglobin if a patient has intravascular hemolysis, use Prussian blue stain or Rous test to detect hemoglobin or hemosiderin in urine
• Myoglobin has a molecular weight of 17,000 and is not catabolized further
• Urine foam is present when urine is vigorously shaken or agitated, which is a mechanical way to test for the presence of protein
• Urine clarity, along with urine color, describes the overall visual appearance of a urine specimen
• Common non-pathologic reasons for cloudy urine include the presence of urates (amorphous urates and phosphates)
• Common pathologic reasons for cloudy urine include the presence of pus cells
• Milky urine may be due to urine mixed with chyle fluid, which can be caused by Wuchereria bancrofti leading to filariasis, hydrocele, and blockage of lymphatic vessels
• Reporting for protein in chemical examination/reagent strip: Trace = 30 mg/dL, + = 100 mg/dL, ++ = 200 mg/dL, +++ = 300 mg/dL
• Non-pathologic causes of urine turbidity include squamous epithelial cells, mucus, amorphous phosphates, and amorphous urates
• Pathologic causes of urine turbidity include abnormal amounts of non-squamous epithelial cells, RBCs, WBCs, bacteria, yeast cells, abnormal crystals, lymph fluid, and lipids
• Urine odor is not routinely performed but can provide significant observations, with different odors indicating various metabolic diseases