Difference between revisions of "Vitamin B7 deficiency"

(Summary of Biotin deficiency)
 
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* Intestinal flora synthesizes significant quantities of biotin.
 
* Intestinal flora synthesizes significant quantities of biotin.
 
* Biotin is recycled in the body and eventually lost in urine and feces.
 
* Biotin is recycled in the body and eventually lost in urine and feces.
 
 
* Biotin (Vitamin B7) is a cofactor in four major carboxylation reactions
 
* Biotin (Vitamin B7) is a cofactor in four major carboxylation reactions
 
# Acetyl-CoA Carboxylase (ACC) - Acetyl-CoA to Malonyl-CoA in Fatty Acid Synthesis
 
# Acetyl-CoA Carboxylase (ACC) - Acetyl-CoA to Malonyl-CoA in Fatty Acid Synthesis
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# Holocarboxylase Synthetase Deficiency -  Autosomal Recessive disorder. Holocarboxylase Synthetase is required to attach biotin to other molecules. Deficiency in this enzyme prevents cells from using Biotin.
 
# Holocarboxylase Synthetase Deficiency -  Autosomal Recessive disorder. Holocarboxylase Synthetase is required to attach biotin to other molecules. Deficiency in this enzyme prevents cells from using Biotin.
 
# Biotinidase Deficiency - Biotinidase is required to release Biotin that is bounded to protein.
 
# Biotinidase Deficiency - Biotinidase is required to release Biotin that is bounded to protein.
 +
 
==Clinical Features==
 
==Clinical Features==
 
* Classical Presentation:
 
* Classical Presentation:
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** Enteritis
 
** Enteritis
 
** Neurological - including AMS, lethargy, hallucinations, paresthesias
 
** Neurological - including AMS, lethargy, hallucinations, paresthesias
 
 
* Holocarboxylase Synthetase Deficiency - presents in the first week of life with:
 
* Holocarboxylase Synthetase Deficiency - presents in the first week of life with:
 
** lethargy
 
** lethargy
 
** hypotonia
 
** hypotonia
 
** vomiting
 
** vomiting
 
 
* Biotinidase Deficiency - presents later in life with:
 
* Biotinidase Deficiency - presents later in life with:
 
** dermatitis
 
** dermatitis
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==Differential Diagnosis==
 
==Differential Diagnosis==
 
 
* DDx involves genetic disorders with impaired carboxylation.
 
* DDx involves genetic disorders with impaired carboxylation.
 
** Biotinidase Deficiency (see above)
 
** Biotinidase Deficiency (see above)
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** Propionic Acidemia
 
** Propionic Acidemia
 
** Pyruvate Carboxylase Deficiency
 
** Pyruvate Carboxylase Deficiency
 
 
* Starvation
 
* Starvation
 
* Medication Use - Antibiotics or Anti-convulsants
 
* Medication Use - Antibiotics or Anti-convulsants
 +
* Other vitamin deficiencies:
  
* Other vitamin deficiencies:
 
 
===[[Vitamin deficiencies]]===
 
===[[Vitamin deficiencies]]===
 
*[[Vitamin A deficiency]]
 
*[[Vitamin A deficiency]]
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==Evaluation==
 
==Evaluation==
 
* Diagnosis is primarily clinical. Routine serum chemistry panel should be checked.
 
* Diagnosis is primarily clinical. Routine serum chemistry panel should be checked.
 
 
* Other Laboratory Studies
 
* Other Laboratory Studies
 
** Newborn Screening
 
** Newborn Screening
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** Plasma Carnitine
 
** Plasma Carnitine
 
** Quantitative Amino Acid levels
 
** Quantitative Amino Acid levels
 
 
** Urine B-Hydroxyisoverlate decreased
 
** Urine B-Hydroxyisoverlate decreased
 
** Urine Biotin decreased
 
** Urine Biotin decreased
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* Stop consumption of raw eggs.
 
* Stop consumption of raw eggs.
 
* Stop anti-convulsant or anti-biotic use.
 
* Stop anti-convulsant or anti-biotic use.
 +
 
==Disposition==
 
==Disposition==
 
* Follow-up with primary care provider or referral to genetic specialist.
 
* Follow-up with primary care provider or referral to genetic specialist.
 +
 
==See Also==
 
==See Also==
 +
  
 
==External Links==
 
==External Links==
 +
  
 
==References==
 
==References==
Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline, 1998.
 
Mock D. Biotin. In: Modern Nutrition in Health and Disease, 9th, Shils M (Ed), Lippincott Williams and Wilkins, Philadelphia 2000. p.459.
 
 
<references/>
 
<references/>
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 +
[[Category:FEN]]

Revision as of 02:11, 15 September 2017

Background

  • Almost all food contain significant quantities of biotin, but it is most found in plants, liver, egg yolk, soybean products, and yeast.
  • Daily biotin requirement is low (150-300 ug/d).
  • Intestinal flora synthesizes significant quantities of biotin.
  • Biotin is recycled in the body and eventually lost in urine and feces.
  • Biotin (Vitamin B7) is a cofactor in four major carboxylation reactions
  1. Acetyl-CoA Carboxylase (ACC) - Acetyl-CoA to Malonyl-CoA in Fatty Acid Synthesis
  2. Pyruvate Carboxylase (PC) - Pyruvate to Oxaloacetate in Gluconeogenesis
  3. Propinoyl-CoA Carboxylase (PCC) - Propinoyl-CoA to Methylmalonyl-CoA in Odd Chain Fatty Acid Metabolism
  4. Methylcrotonyl CoA Carboxylase (MCC) - 3-Methylcrotonyl CoA to 3-Methylglutaconyl CoA in Leucine Metabolism
  • Biotin deficiency is relatively rare. Populations at risk:
  1. Long-term Parenteral Nutrition
  2. Consumption of raw egg whites (bodybuilders or boxers)
  • Secondary biotin deficiency (Multiple Carboxylase Deficiency) is caused by two inherited defects in metabolism:
  1. Holocarboxylase Synthetase Deficiency - Autosomal Recessive disorder. Holocarboxylase Synthetase is required to attach biotin to other molecules. Deficiency in this enzyme prevents cells from using Biotin.
  2. Biotinidase Deficiency - Biotinidase is required to release Biotin that is bounded to protein.

Clinical Features

  • Classical Presentation:
    • Dermatitis - specifically around eyes, nose, mouth
    • Alopecia
    • Enteritis
    • Neurological - including AMS, lethargy, hallucinations, paresthesias
  • Holocarboxylase Synthetase Deficiency - presents in the first week of life with:
    • lethargy
    • hypotonia
    • vomiting
  • Biotinidase Deficiency - presents later in life with:
    • dermatitis
    • neurological symptoms - ataxia, seizures, myoclonus, nystagmus
    • ketoacidosis

Differential Diagnosis

  • DDx involves genetic disorders with impaired carboxylation.
    • Biotinidase Deficiency (see above)
    • Holocarboxylase Synthetase Deficiency (see above)
    • Carnitine Deficiency
    • Methylmalonic Acidemia
    • Propionic Acidemia
    • Pyruvate Carboxylase Deficiency
  • Starvation
  • Medication Use - Antibiotics or Anti-convulsants
  • Other vitamin deficiencies:

Vitamin deficiencies

Evaluation

  • Diagnosis is primarily clinical. Routine serum chemistry panel should be checked.
  • Other Laboratory Studies
    • Newborn Screening
    • Serum Biotinidase Activity decreased
    • Serum Ammonia Levels increased
    • Plasma Carnitine
    • Quantitative Amino Acid levels
    • Urine B-Hydroxyisoverlate decreased
    • Urine Biotin decreased
    • Urine Ketones increased

Management

  • Supplementation of Biotin. Dosage is debated:
    • 150 ug intramuscular injection suggested
    • 5-20 mg/dl have also been used
  • Stop consumption of raw eggs.
  • Stop anti-convulsant or anti-biotic use.

Disposition

  • Follow-up with primary care provider or referral to genetic specialist.

See Also

External Links

References