TABLE 5.

Detailed NICE, ASA, and CAS guidelines for different types of laboratory tests

Test	NICE	ASA	CAS
Haemoglobin or haematocrit	ASA 1–4 – yes	Not routinely, consider when: 1) liver disease, 2) extremes of age, 3) history of anaemia, 4) bleeding, 5) other haematological disorders.	Consider when: 1) liver disease, 2) extremes of age, 3) history of anaemia, 4) risk of significant blood loss, 5) haematological disease, 6) malignancy.
Coagulations/ haemostasis	ASA 1, 2 – not routinely ASA 3, 4 consider – chronic liver disease	Consider when: 1) bleeding disorders, 2) renal dysfunction, 3) liver dysfunction, 4) relevant type and invasiveness of procedure.	Consider when: 1) history of excessive bleeding, or a family history of heritable coagulopathies 2) oral or parenteral anticoagulant therapy 3) conditions or medications associated with impaired coagulation (e.g., liver disease, malnutrition).
Serum chemistries (i.e., potassium, glucose, sodium, renal and liver function studies)	ASA 1 consider in people at risk of AKI ASA 2–4 – yes	Consideration includes: 1) likely perioperative therapies, 2) endocrine disorders, 3) risk of renal dysfunction, 4) risk of liver dysfunction, 5) use of certain medications or alternative therapies.	Electrolytes – may be considered: 1) pituitary–adrenal disease, 2) complicated diabetes, 3) chronic renal failure, 4) liver disease, 5) hypertension, 6) congestive heart failure, 7) malnutrition, 8) for patients taking diuretics, ACEI, ARB, and other therapy affecting electrolytes. Creatinine and eGFR – may be considered: 1) as above for electrolytes, 2) with advanced age, 3) for patients taking medications potentially affecting renal function, 4) for patients receiving direct oral anticoagulants, 5) as required for calculating perioperative risk indices. Fasting glucose level – may be considered: 1) for diabetics – glycaemic control, 2) for patients on glucocorticoid therapy, 3) as screening for BMI > 40 or very high risk of diabetes based on signs and symptoms.
Urine tests	Not routinely. Only if the presence of a urinary tract infection would influence the decision to operate.	Not indicated except: 1) for specific procedures (e.g., prosthesis implantation, urologic procedures) 2) when urinary tract symptoms are present.	N/A
NT-pro-BNP	N/A	N/A	May be considered if: 1) age > 65 years, 2) age 45–65 years with significant cardiac disease, 3) Revised Cardiac Risk Index score > 1.