Janury 22, 2007

Coding for Metabolic Disorders
For The Record
Vol. 19 No. 2 P. 41

One question pharmacogenomics examine is how a patient’s metabolism affects his or her response to different medications. Metabolism is the complex process in which the body turns food into energy. A metabolic disorder affects the production of energy within individual cells by interfering with the body’s metabolism. Most metabolic disorders are genetic, called inborn errors of metabolism. Other metabolic disorders are acquired as a result of diet, toxins, and infections.

Classes of Metabolic Disorders
The following are major classes of metabolic disorders with their respective ICD-9-CM code assignments:

• Disorders of amino acid metabolism (category 270) — Example: phenylketonuria (270.1) and maple syrup urine disease (270.3)

• Disorders of organic acid metabolism (organic acidurias) — Example: alcaptonuria (270.2)

• Disorders of carbohydrate metabolism (category 271) – Example: glycogen storage disease (271.0)

• Lysosomal storage disorders — Example: Gaucher’s disease (272.7)

• Disorders of porphyrin metabolism — Example: acute intermittent porphyria (277.1)

• Disorders of purine or pyrimidine metabolism — Example: Lesch-Nyhan syndrome (277.2)

• Disorders of fatty acid oxidation and mitochondrial metabolism — Example: medium-chain acyl-coenzyme A dehydrogenase deficiency (277.85) and primary carnitine deficiency (277.81)

• Disorders of peroxisomal function — Example: Zellweger syndrome (277.86)

• Disorders of mitochondrial function — Example: Kearns-Sayre syndrome (277.87)

• Disorders of steroid metabolism — Example: congenital adrenal hyperplasia (255.2)

Signs and Symptoms
The following are common signs and symptoms of metabolic disorders:

• growth failure;

• failure to thrive;

• weight loss;

• ambiguous genitalia;

• delayed puberty;

• developmental delay;

• seizures;

• dementia;

• encephalopathy;

• deafness and/or blindness;

• skin rash;

• abnormal pigmentation;

• excessive hair growth;

• dental abnormalities;

• immunodeficiency;

• thrombocytopenia and/or anemia;

• enlarged spleen; and

• excessive urination and/or renal failure.

Diagnosis
Blood and urine tests help confirm the diagnosis of a metabolic disorder. The following are specific tests that may be performed:

• ferric chloride test to detect abnormal metabolites in urine;

• ninhydrin paper chromatography to detect abnormal amino acid;

• guthrie bacterial inhibition assay to detect amino acids in excessive amounts of blood;

• quantitative plasma amino acids; and

• urine organic acids by mass spectrometry.

Other diagnostic studies that may be done include MRI, MR spectroscopy, lumbar puncture, and electromyogram.

Treatment
Metabolic disorders may be treated by one or a combination of the following:

• restriction of diet;

• supplements/replacement of diet;

• vitamins;

• intermediary metabolites;

• dialysis;

• enzyme replacement;

• gene transfer; and

• bone marrow or organ transplantation.

Coding and sequencing for metabolic disorders are dependent on the physician documentation in the medical record and application of the Official Coding Guidelines for inpatient care. Use specific AHA Coding Clinic for ICD-9-CM and American Medical Association CPT Assistant references to ensure complete and accurate coding.

— This information was prepared by Audrey Howard, RHIA, of 3M Consulting Services. 3M Consulting Services is a business of 3M Health Information Systems, a supplier of coding and classification systems to nearly 5,000 healthcare providers. The company and its representatives do not assume any responsibility for reimbursement decisions or claims denials made by providers or payers as the result of the misuse of this coding information. More information about 3M Health Information Systems is available at www.3mhis.com or by calling 800-367-2447.