Specimen requirement

Adult patient:

  EDTA tube

Minimum blood volume: 3 mL

Paediatric patient:

Paediatric EDTA tube

Number of vials: 1

Minimum blood volume: 0.8 mL

Authorisation code required

No

24 Hr available service

Yes

Precaution

Collect one full tube of blood, cap and mix thoroughly.

Send in ice without delay.

Method

Spectrophotometry

Reference interval

(Source:

1. Prellwitz W. Kapps S et al. (UV test, Roche Diagnostics GmbH) Med Welt 1976; 27: 1,277 - 80

2. Reference range for adults and children - Pre-Analytical Considerations 2004)

Clinical indication

Significant hyperammonemia during childhood can be observed with urea cycle defects, many of the organic acidemias, transient hyperammonemia of the newborn (THAN), and fatty acid oxidation defects.

Investigation of unexplained encephalopathy, especially if associated with vomiting.

Result interpretation

Increased plasma ammonia may be indicative of hepatic encephalopathy, hepatic coma in terminal stages of liver cirrhosis, hepatic failure, acute and subacute liver necrosis, and certain inborn errors of metabolic diseases (e.g. urea cycle defects).

Hyperammonemia may also be found with increasing dietary protein intake.

Sulfasalazine and Sulfapyridine interfere in ammonia  analytical measurement.  Patients currently treated with Sulfasalazine and Sulfapyridine might receive false results  of ammonia.

Measurement of uncertainty

See table.

Frequency of measurement

Daily