Orotic acid | Laboratory research

General Information

Orotic acid is a precursor substance for the synthesis of pyrimidine nucleotides, which is synthesized with the participation of mitochondrial enzymes.

Hyperproduction of orotic acid is carried out by two mechanisms:

1. Deficiency of enzymes involved in pyrimidine synthesis, which leads to the accumulation of orotic acid and deficiency of pyrimidine nucleotides in the body (hereditary orotic acid accumulation - by autosomal recessive inheritance). Deficiency of pyrimidine nucleotides is manifested by disruption of cell division processes, which may be clinically manifested by megaloblastic anemia, retardation of growth and development.
2. Genetic disorders of the urea cycle: ornithine-carbamylase deficiency, citrullinemia, arginine succinate accumulation, amino acid transport defect.

When is the survey conducted?

• Patients with ammonia accumulation
• Children with genetic defects of the urea cycle
• Detection of heterozygous females with X-linked transcarbamylase deficiency
• Suspected hereditary accumulation of orotic acid (megaloblastic anemia unresponsive to treatment with B12 and folate, leukopenia with tetropenia, cardiac malformations, intellectual disability, sielme, orotic acid crystals in urine)

Material for examination: Spontaneous urine

Preliminary preparation: it is not necessary

Reference norms:

Infants: < 7 mg/g in relation to creatinine

Children < 10 years: < 5 mg/g in relation to creatinine

Children > 10 years of age and adults < 2 mg/g creatinine ratio

Interpretation of results

An increase in the rate of orotic acid in the urine is observed in the following cases:

• Hereditary increase of orotic acid (orotate phosphoryltransferase and orotidine transferase deficiency)

• Genetic disorders of the urea cycle:

• Ornithine transcarbamylase deficiency
• Citrullinemia
• Increase of arginine succinic acid in urine
• Protein intolerance with lysinuria

A slight increase in orotic acid is possible in pregnancy and during treatment with allopurinol.