The Leeds Teaching Hospitals NHS Trust



Hyperammonaemia results from defective catabolism of amino acids to urea. Recognition and treatment of hyperammonaemia, especially in the neonatal period, is a clinical emergency. If left untreated morbidity and mortality is high.

THE LAB MUST BE ADVISED AT ALL TIMES BEFORE SAMPLING AND SEND TO LAB IMMEDIATELY. Please ensure the time of sampling is noted and that the sample reaches laboratory within 30 minutes of collection. Delayed processing of samples can result in modest increases of ammonia but are less likely to result in significant hyperammmonaemia (i.e. >200 umol/L) unless there has been a significant delay in sample processing (i.e. >12 hours).

Tube 06 (HP) - Heparin Gel
ID Tests&Tubes0008
Additional Information Mildly (<80 umol/L) raised ammonia concentrations are seen relatively commonly. Ammonia can be artefactually elevated to modest levels by haemolysis, prolonged application of a tourniquet/difficult venepuncture, contamination (of skin or tubes) and delayed analysis. In an unwell neonate concentrations may reach around 150 umol/L. Any ammonia >200 umol/L in neonates, >150 umol/L in children, or >100 umol/L in adults requires immediate attention. It is critical to repeat an elevated result immediately to monitor the trend of results. In inherited metabolic disorders the ammonia concentration can rise rapidly and prompt recognition and treatment affects outcomes. In general an ammonia of >200 umol/L is more likely to be due to an underlying metabolic disorder especially if concentrations are rising. If a significantly raised result is obtained / an underlying metabolic disorder is suspected, the on call Metabolic Consultants at the Willink Unit, Manchester (Paediatrics) or the Mark Holland Metabolic Unit, Salford (Adults) must be contacted for further advice. For more information guidelines can found at on the BIMDG (emergency clinical management guidelines) and MetBioNet (investigations of hyperammonaemia) websites (links below).
Turn Around A&E: 1 hour
Day Case: N/A
In-Patient: 6 Hours
Out-Patient: N/A
Send to Blood Sciences Cross Site
Contact For further details please contact Leeds Pathology customer services:
Advice Links to Guidelines:
Collection Con Please avoid prolonged application of a tourniquet. Samples must be brought to laboratory immediately (to arrive in lab <30 minutes after venepuncture). Minimum volume: 500µl plasma
Information for lab staff: Must reach the lab within 30 mins, take the sample to a BMS separate plasma on receipt.

Sample REQ Blood
Ref. Range Notes Blood Sciences reference ranges are available through the useful information and links page:
Units umol/L