Case study - Physical Examination of Urine

Question 1

A urine is received in the laboratory and is fou nd to be yellow and cloudy. Suggest possible causes for this observation.

Answer 1

Although yellow is a normal color seen in urine, a cloudy urine indicates the presence of cells, crystals, bacteria, or fats.

Question 2

A few hours after havi ng eaten a meal, a person notices that his or her urine is red but clear.

1. What benign cause may be given as an explanation for this
   occurrence?
2. What may cause clear red urine on a more regular basis?
3. What may be indicated by a cloudy red urine?

Answer 2

1. What benign cause may be given as an explanation for this occurrence?
   - Genetic predisposition to the pigment found in beets may have caused the urine to be red and clear.
2. What may cause clear red urine on a more regular basis?
   - Porphyrins and free hemoglobin can make the urine appear red and clear
3. What may be indicated by a cloudy red urine?
   - Cloudy red urine indicates the presence of intact red blood cells, many conditions can contribute red blood cells to urine. The cause for the presence of red blood cells in urine should be investigated by a physician.

Question 3

A specific g ravity reading of 1 .000 is obta i ned by reagent strip method on a urine with a pH of 8.0. What should you do before reporti ng this result?

Answer 3

A pH of greater than 7.0 usually lowers the reading of specific gravity on reagent strips. 0.005 should be added to the specific gravity result for alkaline urines tested by reagent strip methods.

Question 4

A specifi c g ravity reading of 1 .030 is obta i ned by reagent strip method on a urine sample and is confirmed by refractive i ndex as g reater than 1 .03 5. What should you do before reporting this result?

Answer 4

Some laboratories report this type of finding as greater than 1 .035. However, other laboratories require that a definitive value be reported. Therefore, diluting the specimen by combining one part of urine with one part distilled water and repeating the refractometer analysis will yield more accurate results.
For example, if a dilution is made with equal parts of urine and water and the refractometer reading is 1 .020 the actual result is 1 .040 ( 1.000 + (0.020 x 2)).
If an extremely concentrated urine requires a higher dilution, the calculation should reflect that. For example, if one part of urine is mixed with two parts of water and the refractometer reading is 1 .025, the actual result is 1 .075 ( 1.000 + (0.025 x 3)).