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Questions and Answers
What clinical significance is indicated by Melanuria?
What clinical significance is indicated by Melanuria?
Which enzyme deficiency is associated with Blue diaper syndrome?
Which enzyme deficiency is associated with Blue diaper syndrome?
Which enzyme deficiency can result in mental retardation?
Which enzyme deficiency can result in mental retardation?
What causes corneal erosion and lesions on the palms, fingers, and soles of the feet in Type 2 Tyrosyluria?
What causes corneal erosion and lesions on the palms, fingers, and soles of the feet in Type 2 Tyrosyluria?
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Which disorder is associated with the lack of Indicanase enzyme?
Which disorder is associated with the lack of Indicanase enzyme?
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What color change is observed in the Nitroso-naphthol test?
What color change is observed in the Nitroso-naphthol test?
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Which of the following statements about Hartnup disease is correct?
Which of the following statements about Hartnup disease is correct?
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What is the primary cause of elevated urinary 5-HIAA levels?
What is the primary cause of elevated urinary 5-HIAA levels?
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Which of the following statements about cystine disorders is incorrect?
Which of the following statements about cystine disorders is incorrect?
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Which of the following amino acids is not involved in the cystinuria form of renal tubular transport defect?
Which of the following amino acids is not involved in the cystinuria form of renal tubular transport defect?
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What is the primary function of platelets in relation to serotonin metabolism?
What is the primary function of platelets in relation to serotonin metabolism?
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Which of the following statements accurately describes the inheritance pattern of cystinuria?
Which of the following statements accurately describes the inheritance pattern of cystinuria?
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What is the immediate precursor to methylmalonic acid in the propionic acid pathway?
What is the immediate precursor to methylmalonic acid in the propionic acid pathway?
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Which of the following is NOT a metabolite of tryptophan metabolism mentioned in the text?
Which of the following is NOT a metabolite of tryptophan metabolism mentioned in the text?
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What is the cause of the 'blue diaper syndrome' mentioned in the text?
What is the cause of the 'blue diaper syndrome' mentioned in the text?
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Which of the following conditions is NOT listed as a potential cause of indicanuria in the text?
Which of the following conditions is NOT listed as a potential cause of indicanuria in the text?
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What is the reason for early diagnosis of Hartnup disease in infants?
What is the reason for early diagnosis of Hartnup disease in infants?
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What is the degradation product of serotonin mentioned in the text?
What is the degradation product of serotonin mentioned in the text?
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Study Notes
Serotonin and Hartnup Disease
- Tryptophan is converted to serotonin by argentaffin cells in the intestine
- Serotonin is carried through the body primarily by platelets
- Degradation product of serotonin is 5-Hydroxyindoleacetic Acid (5-HIAA) and is excreted in the urine
- Elevated levels of 5-HIAA in urine can indicate Argentaffin cell tumors
- Dietary restrictions are necessary as serotonin is found in foods like bananas, pineapples, and tomatoes
- Certain medications like phenothiazines and acetanilids should be withheld for 72 hours prior to specimen collection
Cystine Disorders
- There are two distinct disorders of cystine metabolism: Cystinuria and Cystinosis
- Both disorders are inherited and may have a noticeable odor of sulfur in the urine
- Cystinuria is marked by elevated amounts of cystine in the urine due to a defect in renal tubular transport
Cystinuria
- Inability of renal tubules to reabsorb cystine leads to formation of renal calculi
- Two modes of inheritance:
- Cystine, lysine, arginine, and ornithine are not reabsorbed
- Inheritance pattern is autosomal recessive
- 65% of individuals can be expected to produce calculi early in life
- Diagnosis involves using culture media containing beta-2-thienylalanine and Bacillus subtilis
Tyrosyluria
- Urine may contain excess tyrosine or its degradation products, phydroxyphenylpyruvic acid and p-hydroxyphenyllactic acid
- Three types of Tyrosyluria:
- Type 1: Deficiency in fumarylacetoacetate hydrolase (FAH) leading to generalized renal tubular disorder and liver failure
- Type 2: Lack of tyrosine aminotransferase leading to corneal erosion and lesions on palms, fingers, and soles
- Type 3: Lack of p-hydroxyphenylpyruvic acid dioxygenase leading to mental retardation
- Nitroso-naphthol test produces an orange-red color
Melanuria
- Indicates the overproliferation of melanocytes producing a metastatic malignant melanoma
- Darkening appears after the urine is exposed to air
- Corneal dystrophy and gelatinous drop-like melanuria are associated with Melanuria
Tryptophan Disorders
- Metabolites of tryptophan metabolism include indican and 5-Hydroxyindoleacetic acid (5HIAA)
- Tryptophan metabolism involves:
- Tryptophan being absorbed in the intestine for protein synthesis or converted to indole by bacterial flora
- Indole being reabsorbed into the bloodstream and converted to indican in the liver
- Indican being excreted in the urine, which is colorless until oxidized to indigo blue by exposure to air
- "Blue diaper syndrome" can be an early indicator of Hartnup disease
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Description
Learn about Hartnup disease, a rare inherited disorder affecting the production and excretion of 5-Hydroxyindoleacetic Acid (5-HIAA) and serotonin in the body. Understand how argentaffin cell tumors can lead to elevated levels of 5-HIAA in urine and the dietary considerations for managing the condition.
