Case study- Microscopic examination of Urinary Sediment

Question 1

The urina lysis result below is on a specimen from a patient with metastatic carcinoma.

1. Identify these crystals.
2. Which other crystals appear similar to those seen in this
   urine and may cause confusion in identification?
3. How can these two crystals be differentiated?
4. What chemical findings are consistent with the presence of
   these crystals?
5. What organ system may be affected by this patient’s
   carcinoma?

Answer 1

1. Identify these crystals.
   - Tyrosine
2. Which other crystals appear similar to those seen in this urine and may cause confusion in identification?
   - Needle form or uric acid crystals.
3. How can these two crystals be differentiated?
   - Solubility properties.
4. What chemical findings are consistent with the presence of these crystals?
   - The presence of bilirubin and urobilinogen indicate the possibility of liver dysfunction as do tyrosine crystals.
5. What organ system may be affected by this patient’s carcinoma?

• Liver.

Question 2

The following results were obtained on urine from an adult.

1. Identify these casts and crystals.
2. Explain how microscopic findings correlate with physical
   and chemical findings.
3. Explain any discrepancies observed between the microscopic and chemical findings.

Answer 2

1. Identify these casts and crystals.
   - Hyaline casts and amorphous urates
2. Explain how microscopic findings correlate with physical and chemical findings.
   - The presence of casts is usually accompanied by positive protein findings. Urate crystals can be seen in acidic urine. Trace blood and leukocyte esterase correlates with small numbers of RBCs and WBCs present in the sediment.
3. Explain any discrepancies observed between the microscopic and chemical findings.
   - Although bacteria are present, nitrite is negative. This may be because bacteria are not nitrate reducers, the urine was not in the bladder long enough for the conversion of nitrate to nitrite, or the patient’s diet did not contain nitrates.

Question 3

A urina lysis on a 70-yea r-old male revealed the findings below. He has recently u ndergone u rological procedures.

1. Identify these crystals.
2. Explain how microscopic findings correlate with physical
   and chemical findings.
3. Discuss the pathophysiology behind the microscopic findings in this case.

Answer 3

1. Identify these crystals.
   - Calcium carbonate (notice the dumbbell shape).
2. Explain how microscopic findings correlate with physical and chemical findings.
   - Carbonate crystals require an alkaline environment and are of no clinical significance. The col or and
   turbidity correlate with the presence of RBCs, because blood contributes a brown color to urine as hemoglobin oxidizes.
3. Discuss the pathophysiology behind the microscopic findings in this case.
   - The presence of blood is not unusual in patients who have undergone urological procedures such as cystoscopy.

Question 4

Figures 9-96 and 9-97 display the m i croscopic findings on urine from a 54-year-old female.

1. Identify the structures shown in the images.
   - Oval fat bodies.
2. Explain what reagent strip findings would suggest their presence.
   - No reagent strip tests detect the presence of fats in urine.
3. Suggest some disorders in which these structures may be found in the urine
   - Renal tubule necrosis or any other condition
   resulting in renal tubule cell damage.

Question 5

Figure 9-98 d isplays the m i croscopic findings on urine from a 2 1 -year-old female.
1. Identify the structures shown in the figures.
2. Suggest sources of error in identification of urinary sediment that these structures may present.

Answer 5

1. Identify the structures shown in the figures.
   - Air bubble and hair strand.
2. Suggest sources of error in identification of urinary sediment that these structures may present.

• Inexperienced persons may identify these structures as a cast and an oval fat body.