Clinical Biochemistry Flashcards
What is the purpose of laboratory tests?
Diagnosis
Monitoring
Prognosis
Screening
What is meant by accuracy and precision?
Accuracy - can the method produce the correct result
Precision - can it do this consistently
How is the diagnosis of diabetes made?
- Random venous plasma glucose >11.1mmol/L
- Fasting plasma glucose >7.0mmol/L
- 2 hour plasma glucose >11.1mmol/L in OGTT
- HbA1c >48mmol/mol (Type 2 Diabetes only)
- If asymptomatic, requires confirmation by repeat
testing on another day
How do high levels of HbA1c arise?
High blood glucose levels - glucose cannot be taken into cels so move freely into red cells
When is HbA1c not advised to diagnose diabetes?
Children and young people
Suspected Type 1 diabetes
Symptoms <2 months
High risk patients who are acutely ill
Patients taking medication that may cause rapid glucose rise (e.g. steroids)
Acute pancreatic damage
Pregnancy
Presence of genetic, haematological or illness-related factors that affect HbA1c and its measurement
What is the acute way of monitoring diabetes?
Urine testing: glycosuria, ketonuria
Glucose meter: Measuremeny of capillary blood glucose
What would help in your diagnosis when trying to differentiate the cause of hypoglycaemia?
Deciding between Factitious hypoglycaemia (excessive insulin use) and insulinoma?
C peptide is elevated in insulinoma but not in factitious hypoglycaemia
What is the macrovascular disease assocaited with diabetes?
TIA
Stroke
Angina
MI
Cardiac failure
What is the microvascular disease associated with diabetes?
Diabetic retinopathy
Nephropathy
Erectile dysfunction
Foot problems
What are the Biochemical Measurements in chronic diabetes?
Glucose (self-monitoring of blood glucose)
HbA1c (Glycaemic control)
Urine Albumin/creatinine ratio (Diabetic renal disease - Microvascular screening) - abbreviated to ACR - young people with diabetes should have ACR tested annually from the age of 12 years
Lipids (Macrovascular screening)
How is ACR taken?
Measured in a first pass morning urine specimen once a year
May be measured on a spot sample if a first pass sample is not provided but should be repeated on a first pass specimen if abnormal
How is microalbuminuria confirmed?
In the absence of infection or overt proteinuria - 2/3 specimens have an elevated ACR
