Laboratory Tests in Diabetes Flashcards
why do we use lab tests in diagnosis?
Confirmation or rejection of clinical diagnosis
why do we use lab tests in monitoring?
Natural history or response to treatment
why do we use lab tests in prognosis?
Prediction of course or outcome of the disease
what do we use lab tests in screening?
Detection of sub-clinical disease
what are the stages between a clinical question and a biochemical answer?
what is precision versus accuracy?
what is a reference range?
how is 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
with HbA1-c what are we monitoring?
when do we not use HbA1-c to diagnose diabetes?
Children and young people
Suspected Type 1 diabetes
Symptoms <2 months - not time for hba1c to reflect
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
how are acute presentations of diabetes monitored?
urine testing - glycosuria, ketonuria
GLUCOSE METER-MEASUREMENT OF
CAPILLARY BLOOD GLUCOSE
13 year old female with known type 1 diabetes mellitus admitted to A&E because of drowsiness and vomiting, what tests would you do?
POCT Testing - A Point of Care finger prick test in A&E showed blood glucose of 20 mmol/L.
The FY2 was going to give her some more insulin but decided to confirm the result by sending a blood sample to the lab.
if a result came back from POCT high but low from blood glucose what may this mean?
Contamination when checking POC glucose
21 year old student - thirst, polyuria and weight loss over the last two months; became unwell with flu-like symptoms and began vomiting.
Urinalysis-
Glucose ++++
Ketones ++
Dehydrated, tachypnoeic and generalised abdominal tenderness, admitted to the surgical ward on 40% O2
what is the likely diagnosis?
Diabetic ketoacidosis
what would biochemistry results show in ketoacidosis?
A 21 year old woman with diabetes
mellitus was admitted to the medical
ward for the investigation of recurrent
hypoglycaemic episodes despite her insulin dose being reduced.
what is the most likely diagnosis, how would you reach this?
do an insulin measurement - Insulin 165 mU/L (<13), C-Peptide undetectable
Insulin administration
what would Factitious hypoglycaemia show?
high insulin levels in absence of elevated C-peptide concentrations.
what would insulinoma show?
elevated C-peptide level indicative of insulin-secreting tumour.
what are examples of macrovascular diseases?
TIA, angina, MI, cardiac failure
what are examples of microvascular diseases?
diabetic retinopathy
what are examples of neuropathy?
erectile dysfunction
Biochemical Measurements in Diabetes: Chronic?
Glucose (self-monitoring of blood glucose)
HbA1c (Glycaemic control)
Urine Albumin/creatinine ratio (Diabetic renal disease - Microvascular screening)
Lipids (Macrovascular screening)
HBA1C-GLYCAEMIC CONTROL, what is the risks of complications if poor control progresses?
64 year old lady with Type 2 Diabetes Mellitus
HbA1c 30mmol/mol
(37mmol/mol five months previously).
Home blood glucose monitoring – glucose results consistently 17-18mmol/L
LFTs –
ALT 65 IU/L (<45)
BILIRUBIN 45umol/L (<22)
ALK PHOS 72 IU/L (25-110)
what is the most likely diagnosis?
Haemolytic anaemia
A 56 year old female with a 12 year history of Type 2 Diabetes was found to have a urine albumin/creatinine ratio of 32 mg/mmol (female reference interval <3.5 mg/mmol)
what is the likely diagnosis?
chronic kidney disease
which of the following is a potential cause of raised ACR
Urinary tract infection
Orthostatic proteinuria
Diabetic kidney disease
Angiotensin converting enzyme inhibitors
what should be used to screen for diabetic kidney disease?
ACR
