At SWLP, each discipline handles how grossly abnormal results are communicated to GPs in a different way, depending on the nature of the test.
Below is information about how each discipline makes decisions about when to contact GPs urgently with results.
Chemistry
Results outside the limits in the table below will be telephoned to GP practices during normal working hours.
From 6pm to 10pm weekdays, and 8am to 10pm weekends and bank holidays, results will be reviewed by a clinical scientist/chemical pathologist, and telephoned to the out-of-hours service if required. Values marked in red are a change from the current telephone limits. These limits do not preclude telephoning of any significantly changed results.
| Analyte | Lower limit | Upper limit | Units | Notes |
| Sodium | ≤ 120 ≤ 130 if age under 16 y | ≥ 160 | mmol/L | |
| Potassium | ≤ 2.5 | ≥ 6.5 | mmol/L | |
| Glucose | ≥ 25 ≥ 15 if age under 16 y | mmol/L | ||
| Creatinine | ≥ 350 ≥ 200 if age under 16 y | mmol/L | Results won’t be telephoned if dialysis patient or known CKD unless creatinine has increased by ≥ 100 umol/L from previous result | |
| CRP | ≥ 300 | mg/L | ||
| Calcium | ≤ 1.8 | ≥ 3.5 | mmol/L | |
| Bilirubin (Paediatric) | ≥ 250 | umol/L | ||
| ALT | ≥ 750 | IU/L | ||
| Cortisol | ≤50 | nmol/L | Unless post dexamethasone | |
| CK | ≥ 5000 | U/L | ||
| Digoxin | ≥ 2.5 | umol/L | Sample should be 6h post dose | |
| Lipase | ≥300 | U/L | ||
| Lithium | ≥ 1.5 | mmol/L | ||
| Magnesium | ≤ 0.4 | mmol/L | ||
| Paracetamol | All detectable levels | |||
| Phosphate | ≤ 0.3 | mmol/L | ||
| Phenytoin | ≥ 25 | mg/L | ||
| Salicylate | ≥ 300 | mg/L | ||
| Theophylline | ≥ 25 | mg/L | ||
| Troponin T | ≥ 50 | mg/L | ||
| Urea | ≥30 ≥ 10 if age under 16 y | mmol/L | Results won’t be telephoned if dialysis patient or known CKD unless urea increases by ≥ 10 mmol/L |
Results outside the critical limits stated below will be telephoned to the GP out-of-hours (111) service during the overnight period (10pm to 8am). As well as reviewing renal function, samples with high potassium levels will be checked for haemolysis, age of sample, and possible contamination prior to telephoning.
| Analyte | Lower limit | Upper limit | Units | Notes |
| Sodium | ≤ 115 | ≥ 160 | mmol/L | |
| Potassium | ≤ 2.0 | mmol/L ≥ 6.5 | Potassium levels ≥ 6.5 will not be telephoned overnight if the creatinine is within normal limits | |
| Glucose | ≥ 30 ≥ 15 if patient under 16 years old | mmol/L | ||
| Creatinine | ≥ 350 ≥ 200 if patient under 16 years old | mmol/L | Results won’t be telephoned if dialysis patient or known CKD unless creatinine has increased by ≥ 100 umol/L from previous result | |
| CRP | ≥ 300 | mg/L | ||
| Calcium | ≤ 1.5 | ≥ 3.5 | mmol/L | |
| Bilirubin (paediatric) | ≥ 250 | umol/L |
Haematology
If an abnormal result which meets the criteria set out below is detected within office hours a biomedical scientist will contact the patient’s clinical team (consultant or GP).
If the result is detected out of hours a biomedical scientist will call the clinical team for an in-patient or 111 if the request came from a GP. In this case, clinical queries should do through the on-call registrar.
| HB | ≤70 g/l if new anaemia or fall of 40 g/l in 24 hours |
| Neutrophils | ≤ 0.5 x 10⁹/L unless patient known to be receiving chemotherapy |
| Lymphocytes | ≥ 50 x 10⁹/L unless known CLL |
| Platelets | ≤ 30 x 10⁹/L |
Immunology
Any clinically significant results warranting urgent action are telephoned to the requestor at the discretion of a consultant clinical scientist
Microbiology
In microbiology, there are no reference ranges per se. Significant urgent results are telephoned or communicated by other means on the judgement of the clinical microbiologists.
