A 32-year-old female presented to the Emergency Department because of myalgia, m

Question

A 32-year-old female presented to the Emergency Department because of myalgia, muscle weakness, and severe abdominal pain often associated with nausea. Similar episodes had occurred since she was 18. She also complained of previous bouts of depression. She stated that these symptoms would occasionally disappear, but always returned especially around the onset of her menstrual period. Prior to her current episode, she had been prescribed antibiotics for a urinary tract infection. Routine blood and urine laboratory results were normal, as well as a CT scan of her abdomen and pelvis. Two days after admission, the physician was notified by the clinical laboratory that her urine sample had turned a deep red color after sitting on the laboratory bench.

1. What is a likely diagnosis of this patient’s disorder based on the preliminary data?

2. What additional tests should be performed?

3. What two specific analytes would aid in the differential diagnosis of this patient’s condition?

4. Why did this patient not experience cutaneous symptoms?

5. How would the analysis of fecal porphyrins aid in the differential diagnosis?

6. Would the Watson-Schwartz test be of use in this case?

7. What is the biochemical defect in this case?

Explanation / Answer

1.      The likely diagnosis would be acute intermittent porphyria which is a genetic metabolic disease condition which affects the production of heme in the body due to the deficiency of porphobilinogen deaminase.

2.      Additional tests would be:

·         Porphobilinogen deaminase

·         Porphobilinogen

·         Electrolytes

·         Antinuclear antibody

·         White blood cells

·         Creatinine kinase

·         Enzyme assay of alanine transaminase, aspartate transaminase

·         Norepinephrine and epinephrine

3.      Serum amylase and lipase would differentiate it from pancreatitis and liver function tests (specifically alanine aminotrasferase) would differentiate it from hepatitis and cholecystitis.

4.      There are two types of porphyria which are acute porphyria with neuropathy, abdominal pain and autonomic instability and cutaneous porphyria along with photosensitive rashes on the skin. This patient presented with neurovesical porphyria which is the first type and not cutaneous porphyria and this is the reason as to why she did not present with cutaneous manifestations.

5.      Fecal porphyrins would aid in the diagnosis as they would be elevated in acute intermittent porphyria

6.      This test would be useful here as it is the screening test for acute intermittent porphyria.

7.      The biochemical defect in this case is the deficiency of porphobilinogen deaminase which is essential in the production of heme.

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