Biochemistry
AKI: Stage 1
All AKI stage 1 results will be phoned if the potassium is ≥6.0mmol/L.
AKI: Stage 2 and 3
All new stage 2 and 3 results will be phoned out.
| Test | Lower limit | Higher limit | Rules and exceptions |
|---|---|---|---|
| Potassium (mmol/L) | ≤2.5 | ≥6.5 | See below for specific rules and exceptions |
Potassium: Bicarbonate results of ≥30mmol/L
In patients where the bicarbonate result is ≥30mmol/L, a lower limit of ≤3.0mmol/L is used.
≤2.5mmol/L should not be phoned in post-dialysis samples.
Potassium: Pre-dialysis results
The higher limit of ≥6.5 includes pre-dialysis results.
If the request is from a satellite dialysis unit such as Darlington Dialysis Centre (DDC), Stockton Dialysis Centre (SDC) or North Oremsby Dialysis Centre (NODC) the result is phoned directly to the unit. These results will be phoned the next day if the unit is closed.
On Saturdays and the unit is closed, the result is phoned to the on-call renal consultant.
Potassium: Post-dialysis results
A high limit of ≥5.5 applies to post-dialysis results only.
These results will be phoned on any dialysis patient in the case of failed of incomplete dialysis.
| Test | Lower limit | Higher limit | Rules and exceptions |
|---|---|---|---|
| Sodium (mmol/L) | ≤120 | ≥150 | Lower limit of ≤130 for under 16s |
| Bicarbonate (mmol/L) | ≤10 | – | – |
| Creatinine (µmol/L) | – | ≥350 | See below for specific rules and exceptions |
Creatinine: No previous results
Results will be phoned if there is no previous result of greater than ≥350µmol/L.
Creatinine: Renal function results
Results will be phoned for renal function results if the creatinine result increases by more than 50% of the previous concentration.
| Test | Lower limit | Higher limit | Rules and exceptions |
|---|---|---|---|
| Paediatric creatinine (µmol/L) | – | ≥200 | If no previous value greater than ≥200µmol/L |
| Urea (mmol/L) | – | ≥30 | Higher limit of ≥10 for under 16s |
| Glucose (mmol/L) | ≤2.5 | ≥20 | See below for specific rules and exceptions |
Glucose: History of diabetes
If the patient has a known history of diabetes, the higher limit used is ≥30. If the patient has no history of diabetes than the higher limit of ≥20 is applicable.
Glucose: Under 16's
If the patient is under 16 years of age then the higher limit of ≥20 is used.
| Test | Lower limit | Higher limit | Rules and exceptions |
|---|---|---|---|
| Corrected calcium (mmol/L) | ≤1.8 | ≥3.0 | – |
| Phosphate (mmol/L) | ≤0.35 | – | – |
| Magnesium (mmol/L) | ≤0.40 | – | – |
| Total Bilirubin (µmol/L) | – | ≥200 | Paediatric samples only if no previous result ≥200µmol/L |
| Direct Bilirubin (µmol/L) | – | ≥20 | Neonates only |
| ALT/AST (U/L) | – | ≥600 | See below for specific rules and exceptions |
ALT/AST: Paediatric samples
All paediatric results ≥500 are telephoned out.
| Test | Lower limit | Higher limit | Rules and exceptions |
|---|---|---|---|
| Hs-troponin (ng/L) | – | ≥120 | JCUH A&E results only |
| Lithium (mmol/L) | – | ≥1.0 | Check last dose/sampling interval |
| Digoxin (µg/L) | – | ≥2.0 | Check last dose/sampling interval |
| Phenytoin (mg/L) | – | ≥25 | 3.5 hours post dose or 2.5 hours post dose IV |
| Carbamazepine (mg/L) | – | ≥25 | Check last dose/sampling interval |
| Theophylline (mg/L) | – | ≥25 | 2 to 4 hours post dose or trough |
| Valproate (mg/L) | – | ≥150 | Trough level |
| Gentamicin (mg/L) – Pre dose | – | ≥2 | – |
| Gentamicin (mg/L) – Post or random dose | – | ≥10 | – |
| Vancomycin (mg/L) – Pre dose | – | ≥20 | – |
| Vancomycin (mg/L) – Post dose | – | ≥40 | – |
| Teicoplanin (mg/L) – Pre dose | ≤10 | – | – |
| Teicoplanin (mg/L) – Pre dose | – | ≥60 | – |
| Bile acids (µmol/L) | – | ≥19 | Results will be phoned to Maternity Day Unit |
| Urate (µmol/L) | – | ≥340 | Pregnant patients only |
| Ethanol (mg/L) | – | ≥4000 | Higher limit of ≥100mg/L in paediatric patients |
| Ammonia (µmol/L) | – | ≥100 | – |
| CK (U/L) | – | ≥5000 | – |
| Amylase (U/L) | – | ≥500 | – |
| Lactate (mmol/L) | – | ≥2 | Only for the first presentation per admission or stay |
| Iron (µmol/L) | – | – | All paediatric results to be phoned |
| Cortisol (nmol/L) | ≤100 | – | – |
Cortisol: Expected low results
Unless dexamethasone suppression test, known Addison’s/adrenal insufficiency patient, or on steroids.
| Test | Lower limit | Higher limit | Rules and exceptions |
|---|---|---|---|
| Paracetamol | ≤120 | ≥150 | Lower limit of ≤130 for under 16s |
| Salicylate | ≤10 | – | – |
The below limits apply to GP samples only. The results can be phoned the next day if the practice is closed with the exception of CRP, TSH and Hs-Troponin I. These results are then phoned to the GP deputising service.
| Test | Lower limit | Higher limit | Rules and exceptions |
|---|---|---|---|
| CRP (mg/L) | – | ≥300 | Phoned out urgently |
| CA125 (kU/L) | – | ≥35 | Only if no previous results of ≥35kU/L |
| PSA (µg/L) | – | ≥10 | Only if no previous results of ≥10µg/L |
| Triglyceride (mmol/L) | – | ≥20 | Only if no previous results of ≥20mmol/L |
| TSH (mU/L) | – | ≥60 | Only if no previous history of hypothyroidism or sudden change after long period of stability |
| Hs-Troponin I (ng/L) | – | >3 |
Phone limits are based on:
- RCPath document G158 – The communication of critical and unexpected pathology results October 2017
- NENC Biochemistry Specialty Reference Group consultation October 2023
- Local discussion with endocrinology and renal medicine
Haematology
New findings:
- White cell count greater than 30 x 109/l
- Neutrophil count less than 1.0 x 109/l
- Platelet count less than 50 x 109/l
- Haemoglobin less than 75g/l
- INR results ≥ 5.0
Where clinical areas do not have access to WebICE:
- PT greater than 18 seconds
- APTT greater than 44 seconds
- Clauss fibrinogen less than 2g/L in maternity patients; less than 1g/L in all other patients
- D-dimer greater than 10.00 µg/mL
The on-call Haematology medical team will be informed of:
- All new probable acute leukaemias and chronic myeloid leukaemias
- New patients with platelets less than 20 x 109/l (not on ITU)
- New patients with neutrophils less than 0.5 x 109/l (not receiving chemotherapy)
- New patients with haemoglobin less than 80g/L with significant spherocytes or fragments on the film.
Coagulation
| Test | Limit | Rules and exceptions |
|---|---|---|
| PT | >180 seconds | Any concerns regarding prolongation of the PT will be also be phoned |
| APTT | >240 seconds | Any concerns regarding prolongation of the APTT will be also be phoned |
| APTTR (if on Heparin) | >3.0 | – |
| Clauss fibrinogen | <1g/L | Limit of <2g/L for maternity patients |
| D-dimer | >10.00µg/ml | – |
| INR | >5.0 | – |
Grossly abnormal PT and APTT
Grossly abnormal PT and APTT results will be telephoned immediately to the requesting location as patient is at high risk of bleeding, even if the patient is on a Heparin infusion.