Vitamin B7 deficiency: Difference between revisions

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==Clinical Features==
==Clinical Features==
===Classical Presentation===
===Classical Presentation===
* Dermatitis - specifically around eyes, nose, mouth
* [[rash|Dermatitis]] - specifically around eyes, nose, mouth
* Alopecia
* [[Alopecia]]
* Enteritis
* Enteritis ([[diarrhea]], [[nausea/vomiting]])
* Neurological - including [[AMS]], lethargy, [[hallucinations]], [[paresthesias]]
* Neurological - including [[AMS]], [[lethargy]], [[hallucinations]], [[paresthesias]]


===Holocarboxylase Synthetase Deficiency===
===Holocarboxylase Synthetase Deficiency===
Presents in the first week of life with:
Presents in the first week of life with:
* lethargy
* [[altered mental status (peds)|Lethargy]]
* hypotonia
* Hypotonia
* vomiting
* [[Vomiting]]


===Biotinidase Deficiency===
===Biotinidase Deficiency===
Presents later in life with:
Presents later in life with:
* dermatitis
* [[rash|Dermatitis]]
* neurological symptoms - [[ataxia]], [[seizures]], myoclonus, nystagmus
* Neurological symptoms - [[ataxia]], [[seizures]], myoclonus, [[nystagmus]]
* ketoacidosis
* [[Ketonemia|Ketoacidosis]]


==Differential Diagnosis==
==Differential Diagnosis==
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** Pyruvate Carboxylase Deficiency
** Pyruvate Carboxylase Deficiency
* Starvation
* Starvation
* Medication Use - Antibiotics or Anti-convulsants
* Medication Use - [[Antibiotics]] or [[anticonvulsants]]
* Other vitamin deficiencies:
* Other vitamin deficiencies:


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==Management==
==Management==
* Supplementation of Biotin. Dosage is debated:
* Supplementation of [[Biotin]]. Dosage is debated:
** 150 ug intramuscular injection suggested
** 150 ug intramuscular injection suggested
** 5-20 mg/dl have also been used
** 5-20 mg/dl have also been used


* Stop consumption of raw eggs.
* Stop consumption of raw eggs.
* Stop anti-convulsant or anti-biotic use.
* Stop culprit anti-convulsant or anti-biotic


==Disposition==
==Disposition==
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==See Also==
==See Also==
 
*[[Vitamin deficiencies]]
*[[Inborn errors of metabolism]]


==External Links==
==External Links==

Latest revision as of 17:02, 29 September 2019

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.

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 risk factors

  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

Holocarboxylase Synthetase Deficiency

Presents in the first week of life with:

Biotinidase Deficiency

Presents later in life with:

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 anticonvulsants
  • 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 culprit anti-convulsant or anti-biotic

Disposition

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

See Also

External Links

References