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
Clinical Biochemistry and Metabolic disease II
Dr Vivion Crowley
Consultant Chemical Pathologist
St James’s Hospital
Biochemical Investigation of a Patient
with Suspected Hypocalcaemia?
What are the causes of Hypocalcaemia
What are the clinical features of Hypocalcaemia
Does the patient have “True HypoCa”
What is the Plasma PO4 level?
Is there a clinically apparent cause of Hypocalcaemia?
What about Calcium-reducing medications
What is the plasma PTH Level?
43 yr old male with renal failure due to analgeisc nephropathy
What is the cause of his HypoCa?
Explain the abnormal findings?
70 yr old male presented with the Hx of
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?
Biochemical test play an essential role in
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
Disorders of Endocrine Glands
Disorders involving the Pituitary Gland
Hypopituitarism- Clinical Manifestations
Hypopituitarism – Biochemical investigation
Acromegaly - Excess GH secretion
Acromegaly – clinical signs
Biochemical Investigation of Suspected GH Excess
Cushings’ syndrome - Excess circulating cortisol
Investigation of suspected Cushing’s syndrome
Does the patient have Cushing’ syndrome?
What is causing the patient’s Cushing’ syndrome?
Does the Patient have Cushing’s 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
What is the underlying cause of Cushing’s syndrome?
Hyperprolactinaemia – clinical presentation
Biochemical investigation of Hyperprolactinaemia
What are the commonly measured TFTs?
– useful in the diagnosis of T3 toxicosis
- Normal T4 and suppressed TSH
Patterns of Thyroid Function Tests
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)
Biochemical abnormalities in Addison’s Disease
Take blood sample for plasma Cortisol and ACTH levels before
Plasma Cortisol Plasma ACTH
NB: Dexamethasone does not interfere with cortisol assay
Biochemical Diagnosis of Addison’s disease
Biochemical paraneoplastic syndromes
Case 1: Hx
Case 1: TFTs
Case 1: TFTs (cont)
Case 1: Differential Dx
Case 2: History
Case 2: Repeat TFTs
Central Hypothyroidism – Referred to endocrine service SJH
Case 2: Endocrine assessment
Case 3: Background
- Put on some additional test
Case 3: Endocrine tests
Case 3: Diagnosis
Case 4: background
Case 4: Dx?
Paired urine and plasma osmolality are very useful
in directing management of
24 yr old male
Unwell – Hx of admissions with hypoNa