Case study- Metabolic diseases

Question 1

A 42-yea r-old man p resented to the emergency
room with hematu ria and pa in. He reported a history of kid ney
stones going back to his teen yea rs and sa id he had been told he
had a metabolic d i sorder. A urinalysis gave the followi ng resu lts

1. What metabolic disorder does this patient most likely have?
2. Are these typical findings for kidney stones?
3. What causes this disorder?
4. Name a disorder with which this may be confused.
5. Name three major differences between these two disorders.
6. What further tests could be done?

Answer 1

1. What metabolic disorder does this patient most likely have?
   - Cystinuria.
2. Are these typical findings for kidney stones?
   - The patient history fits with kidney stones even though cystine stones are not as common as calcium stones.
3. What causes this disorder?
   - The patient cannot reabsorb cystine and other amino acids such as arginine, lysine, and ornithine; and excretes these substances at high levels. This is an
   autosomal recessive disorder.
4. Name a disorder with which this may be confused.
   - Cystinosis.
5. Name three major differences between these two disorders.

• a. Aminoaciduria in cystinuria is limited to arginine, cysteine, lysine, and ornithine; aminoaciduria in cystinosis is generalized.
  b. Cystine calculi/stones may be found in cystinuria;
  but rarely in cystinosis.
  c. Cystine crystals are deposited in bone marrow and
  body tissues in cytinosis but not in cystinuria

6. What further tests could be done?
   - Cyanide nitroprusside, silver nitroprusside

Question 2

A 37-yea r-old female was seen by her physician because she was havi ng nausea and we ight loss. No abnormal ities were found u pon physical exami nation, h oweve r the patient’s history include the recent employment with a company
that performs lead-a batement for va rious fa cil ities. The patient
does n ot experience any photosensitivity but her urine does become reddish upon standing.

1. What is the disorder that this patient displays?
2. What further testing may be performed and what are the
   expected results in this case?
3. Why is this patient not sensitive to sunlight?

Answer 2

1. What is the disorder that this patient displays?
   - Acquired porphyria due to lead intoxication.
2. What further testing may be performed and what are the expected results in this case?
   - A common method for separating the
   individual porphyrin is high performance liquid chromatography which may be performed in the chemistry department. ALA will be increased, porphobilinogen will be normal or slightly increased, coproporphyrins will be increased, and uroporphyrins will be normal or slightly increased.
3. Why is this patient not sensitive to sunlight?
   - Persons with cutaneous porphyria demonstrate photosenstivity. This patient’s condition is acquired and not an inherited disorder, therefore photosensitivity is not experienced.

Question 3

A 4-month-old i nfant was brought to the emergency department beca use of vomiting and diarrhea . The physical exami nation revea led an enlarged l iver and spleen. Urinalysis testing gave the followi ng resu lts

1. The symptoms and urine findings shown by this infant may
   indicate which diagnosis?
2. What is the most common form of this disorder and what
   is the cause?
3. What additional test would be helpful in establishing a
   diagnosis and what are the expected results?

Answer 3

1. The symptoms and urine findings shown by this infant may indicate which diagnosis?
   -Symptoms of failure to thrive, diarrhea, vomiting, jaundice, and possible liver and kidney failure in this infant along with the presence of tyrosine crystals in the urine point to tyrosinemia
2. What is the most common form of this disorder and what is the cause?
   -The most common form of tyrosinemia, Type I, is caused by decreased levels of the enzyme
   fumarylacetoacetate hydrolase needed to break down
   tyrosine.
3. What additional test would be helpful in establishing a diagnosis and what are the expected results?
   -Urinary aminoacid studies should indicate that there is a generalized aminoaciduria with a predominance of tyrosine. In addition, tests should be performed to rule out the possibility of these crystals been caused
   by drug metabolites.