Speciality Immunoassays and Reagents

Vitamin H (Biotin) ELISA

Vitamin H (Biotin) ELISA				Catalog # VITH.96
Format	Competitive assay				View product insert
Size/Volume	96 wells
Species	human				Request Quote
Sample Type	serum, plasma, urine
Sample Preparation	sample dilution
Sample Size	50 uL
Standard Curve Range	12.3 - 1000 ng/L
Sensitivity	-
Assay Length	1.5 hr

Summary and explanation

Biotin, also known as vitamin H, is of great importance for the biochemistry of the human organism. As a prosthetic group of mitochondrial enzymes (carboylases), biotin plays a central role as a CO2-carrier in important metabolic reactions such as gluconeogenesis, synthesis of fatty acids and metabolism of amino acids. Furthermore, biotin influences the growth and maintenance of blood cells, sebaceous glands, skin, hair and nails. Next to the free form of biotin, the biotin linked to lysin, also known as biocytine, can also be utilized as a vitamin source by the body, after cleavage from the protein by the enzyme biotinidase.

In nature, biotin is very common. It can be found in bacteria and mushrooms, as well as in higher plant life and animal tissue - especially in liver and kidney. However, the biotin availability in some food is very slim. Amounts worth mentioning can only be found in yeast, soya beans, nuts, cauliflower, lentils, oats, wheat germ and in egg yolk whereas fruits, milk products and most vegetables only contain small amounts. Solely, the amount of biotin is not the decisive factor, but rather the bioavailability. The bioavailability varies very strongly and depends on the kind of food and also on the extent to which biotin is protein-bound. Whereas, for example, in plants, biotin is available in the free form, food coming from animals contains mostly protein-bound biotin. Only after proteolytic reduction in the small intestine followed by a cleavage with intestine (pancreas)-biotinidase is the biotin available in the free absorbable form.

Biotin which is synthesized endogenously by flora of the intestine is not reabsorbed in the colon, but is stored as protein-bound biotin in the bacteria of the intestine and is thus not available to cover the biotin requirement of the organism. The treatment of food also causes losses in biotin. Wheat, as a whole grain, contains 4 times as much biotin as all-purpose flour (Type 405). The alimentary utilization of biotin is estimated at 50 %, so that a biotin deficiency can easily result. Malnutrition as well as an inherited disorder in biotin metabolism (singular or multiple deficiency in carboxylase, biotinidase deficiency) can lead to a biotin deficiency. Furthermore, circumstances of life, where an increased biotin demand exists (pregnancy, nursing, athletic activities, pathological conditions) may cause a biotin malnutrition. A variety of disorders on hair, skin and nails are the medically relevant consequences of a biotin deficiency. The symptoms range from brittle, splintered fingernails to different forms of alopecia to scaly erythematous and seborrheic dermatitis. Animals have also been observed with similar illnesses, ranging from larger skin detachments, epidermal crust development, as well as a hyper- and parakeratosical change in mucous membrane.

With an average nutrition, a daily ingested amount of 30 - 100 g of biotin is considered.

The normal biotin plasma level ranges from 200 - 1200 ng/l. An optimum plasma concentration of biotin in healthy humans is considered to be 400 ng/l. Since these values can differ by 100% from one day to the next, it is advised that a biotin detection must be carried out on 2 - 3 consecutive days to ensure a correct diagnosis of the deficiency as well as to observe the development of a substitution therapy.

Independent from the cause, a biotin deficiency always exists when the plasma biotin level is below 100 ng/l. In this case, substitution should definitely occur.

If biotin is taken externally, excessive amounts are not absorbed and excreted with the feces, whereas absorbed amounts of biotin, which exceed the storage capacity of the organism are eliminated in the urine. Shortly after an oral take up of biotin, the biotin concentration in the plasma increases several times, but after 24 h the average value is reached again. In pharmacological dosages (mg-range), biotin stimulates the differentiation of epidermal cells. The effect is independent from the biotin status and influences all keratin structures, like hair, skin and nails.

Recent studies have shown that the elderly with 300 ng/l have a lower biotin level than younger adults and children, whose optimal range lies between 400 and 500 ng/l. The biotin concentration in urine of all age groups is approximately 30 to 40 times higher than the respective serum concentration.

The quantitative detection of biotin in serum, plasma and urine is easier and faster to carry out with the ELISA than with the common microbiological procedures and isotope dilution tests. The samples can be applied directly to the test after required dilution.

Cross-reactivity

The cross-reactivity of the Biotin test was investigated with structurally similar substances. With exception of biocytin (protein-bound biotin), there was no significant cross-reactivity with other substances similar to biotin.

substance	cross-reactivity (%)
biotin	100
biocytin	83
biotin-d-sulfoxid	34.7
biotin-l-sulfoxid*	24.5
biotinsulfon	28.2
bisnorbiotin	5.5

*biotin-l-sulfoxid is contaminated with 3.3 % biotin and a not quantified amount of biotin-d-sulfoxid.

 

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