Clinical Biochemistry Questions Flashcards
Why use laboratory tests?
Diagnosis
Monitoring
Prognosis
Screening
What is the reference range?
Mean of all patients +/-2 standard deviations
What is NOT used to diagnose diabetes?
Pin prick glucose meter
What are the diagnostic tests for diabetes?
Random venous plasma glucose
2hr plasma glucose
Fasting plasma glucose
HbA1c
What is a high Random venous plasma glucose ?
> 11.1mmol/L
What is a high 2hr plasma glucose?
> 11.1mmol/L
What is a high fasting plasma glucose?
> 7mmol/L
What is a high HbA1c?
> 48mmol/L
How is a diagnosis confirmed in an asymptomatic patient?
Repeat testing on another day
Using another test
What is an OGTT?
Oral glucose tolerance test
Why does HbA1c tell us a patients control?
Independent of insulin, glucose moves freely into RBC
Where is HbA1c located?
Intracellularly
When is HbA1c not used?
Young people Symptoms <2mo Suspected type 1 Acute illness Medications that cause a rapid glucose rise (steroids) Acute pancreatic damage Pregnancy Hematological illness
How is diabetes monitored?
Urine - glucose, ketones
Glucose meter measurement
A patients pin prick test for glucose comes back high but labs are confirmed hypoglycaemic, why?
Failure to clean the finger on pin prick testing
A patient presents with thirst, polyuria, weight loss over 2 mo.
Vomiting, ketones and glucose is elevated.
Patient is dehydrated and tachypnoeic, what is likely to be the cause?
Diabetic ketoacidosis
Why is bicarbonate low in DKA?
Bicarbonate is used as a buffer against falling pH
What would you suspect carbonates to be in a DKA patient?
Low
What would you suspect Potassium to be in a DKA patient?
Depends - have they been vomiting
low if so
Why might creatinine be elevated in a patient in DKA?
Elevated - vomiting causes dehydration which means more work for the kidneys
What is factitious hypoglycaemia?
High insulin in absense of elevated C-peptide (overuse of insulin)
What is the cause of elevated C-peptide?
Insulinoma
If a patients insulin is very high but their C-peptide is very low, what is likely to be the cause?
Overuse of insulin
What are the major chronic complications of diabetes?
Erectile disfunction
Nephropathy
Foot problems
Micro/macrovascular disease
Why is HbA1c used in diabetes?
It tells us about the quality of glycaemic control
What factors are measured to assess a diabetic patient?
Glucose
HbA1c
Urine Albumin/creatinine ratio
Lipids
What does Urine Albumin/creatinine ratio
tell us?
Renal function - risk for diabetic renal disease
A patient has low HbA1c and elevated bilirubin - what is likely to be the cause?
Haemolytic anaemia
