Clinical Biochemistry and Metabolic disease II. Dr Vivion Crowley Consultant Chemical Pathologist St James’s Hospital Dublin. Biochemical Investigation of a Patient with Suspected Hypocalcaemia?. What are the causes of Hypocalcaemia. Low albumin Artefact Chronic renal failure
Dr Vivion Crowley
Consultant Chemical Pathologist
St James’s Hospital
with Suspected Hypocalcaemia?
What is the cause of his HypoCa?
Explain the abnormal findings?
Bone pain and malaise
What is the corrected Ca level?
What further investigations would you consider?
The PTH is 10 (9-65), is the HyperCa PTH dependent or independent?
What is the likely diagnosis?
What is MGUS?
the management of endocrine disease
Screening – TSH in neonatal hypothyrroidism
Case finding – e.g. Pentagastrin test in medullary thyroid ca
Diagnosis – over or under production of hormones
Monitoring response to Rx or recurrence
Does the patient have Cushing’ syndrome?
What is causing the patient’s Cushing’ syndrome?
Overnight dexamethasone suppression (1mg at midnight)
Normal = 9am cortisol < 50nmol/l
24 hour urinary free cortisol
Midnight cortisol – looking for loss of cicardian rhythm
Low dose dexamethasone suppression test (0.5mg qds for 48hour)
Normal = 48hr cortsiol < 50 nmol/l
– useful in the diagnosis of T3 toxicosis
- Normal T4 and suppressed TSH
Ensure that hypoglycaemia is documanted by laboratory blood/plasma glucose
Determination on a sample collected into a fluoride tube
5hour OGTT - hypoglycaemia may occur between 2-5 hours after glucose load
Definitive investigation for fasting Hypoglycaemia:
Supervised - 72 hour prolonged fast
If pt develops neuroglycopaenic symptoms then measure
Plasma Glucose, Insulin, C-pepetide
Other routine invsetigations: U/E, LFTs, ? Endocrine
Urine output > 3 litres/day
(explain the difference between polyuria and urinary frequency)
Confirm polyuria - 24hr urine collection
Causes of polyuria
Drugs - diuretics, lithium
Diabetes mellitus - fasting ± random glucose, OGTT
Chronic renal failure - plasma urea & creatinine, Creatinine clearance
- elbows, knees, buccal mucosa, recent scars (ACTH levels)
Take blood sample for plasma Cortisol and ACTH levels before
Plasma Cortisol Plasma ACTH
NB: Dexamethasone does not interfere with cortisol assay
Central Hypothyroidism – Referred to endocrine service SJH
- Put on some additional test
Paired urine and plasma osmolality are very useful
in directing management of
Unwell – Hx of admissions with hypoNa