Clinical Biochemistry and Metabolic disease II

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Clinical Biochemistry and Metabolic disease II
Dr Vivion Crowley Consultant Chemical
Pathologist St Jamess Hospital Dublin
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Biochemical Investigation of a Patient with
Suspected Hypocalcaemia?
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What are the causes of Hypocalcaemia

• Low albumin
• Artefact
• Chronic renal failure
• Hypoparathyroidism
• PTH resistance
• Pseudohypoparathyroidism
• Hypomagneaemia
• Vitamin D deficiency
• Vitamin D resistance states
• Medications
• Miscellaneous

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What are the clinical features of Hypocalcaemia

• PNS numbness, tingling, muscle cramps
• CNS Psychiatric symptoms e.g irritability,
  rarely tetany and seizures
• Basal ganglia calcification
• Chvosteks sign
• Trousseaus sign

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Does the patient have True HypoCa

• What is the corrected Ca?
• Evidence of artefact? - K EDTA contamination
• What is the local reference range?

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What is the Plasma PO4 level?

• High PO4
• Hypoparathyroidism
• Renal failure
• Low/Normal PO4
• Vitamin D
• Renal failure post dialysis/treatment
• Other causes
• NB PO4 levels are affected by many factors and
  cannot be relied upon alone

• Does the patient have Hypomagnesaemia?
• Causes PTH resistance
• Must correct Mg deficit before improvement in Ca
  levels

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Is there a clinically apparent cause of
Hypocalcaemia?

• Chronic Renal Failure high PO4, low 1, 25 (OH)
  Vit D
• Pancreatitis precipitation of Ca and Mg in
  necrotic adipose tissue
• Sepsis low albumin
• Post thyroid or parathyroid surgery Hungry
  bone syndrome
• Tumour lysis syndrome high PO4 precipitates Ca
• Rhabdomyolysis as for TLS, marked increase in
  CK
• Osteoblastic metastases

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What about Calcium-reducing medications

• Bisphosphonates
• Calcitonin
• Phosphate
• Foscarnet
• Pentamidine

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What is the plasma PTH Level?

• Low PTH
• Hypoparathyroidism
• Idiopathic Di George syndrome
• Autoimmune
• Post-surgical
• Hypomagnesaemia
• High PTH
• Vitamin D deficiency or resistance (secondary
  Hyperparathyroidism)
• Psuedohypoparathyroidism
• Severe liver disease
• Chronic renal failure
• NB Check Vit D levels in secondary
  hyperparathyroidism

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43 yr old male with renal failure due to
analgeisc nephropathy Na 134 K
5.8 Urea 42.2 Creat 650 Ca 1.82 PO4
2.53 Alb 37 ALP 200 PTH 425 What is the
cause of his HypoCa? Explain the abnormal
findings?
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70 yr old male presented with the Hx of Bone
pain and malaise Ca 3.4 PO4 1.5 Alb 30 TP
110 ALP 100 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?
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Case 2

• GM 73 old female
• Admitted April and July 2008 with
• Left sided weakness, slurred speech, confusion
• Mild seizures on 2nd admission
• Poor oral intake, weight loss (57.5 kg on 1/5/08
  48.5 kg on 22/07/08)
• PMH HTN, Hypercholesterolaemia, OA
• Medication Aspirin, Doxazocin, Perindopril
• Amlodipine, Omeprazole
• Pravastatin

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Case 2 cont.

• Routine bloods
• GluR 5.5 mmol/L
• U/Es urea 20.95.4 mmol/L, creatinine 20266
  umol/L (after rehydration), Na 140 mmol/L, K 2.9
  mmol/L
• Ca 1.24 mmol/L Albumin 28 g/L, PO4 1.16 mmol/L
  (ref. 0.8-1.4)
• LFTs NAD

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Case 2 cont.

• Laboratory tests cont.
• FBC- Hb 10.3, MCV 77.7, tTG 1.6, iron 2 (ref
  14-3) umol/L, transferin sat. 7 (ref 30-40) ,
  ferritin and folate NAD
• TFTs TSH 0.71 mU/L, fT4 23 pmol/L

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• 25OH Vit D 32 nmol/L (gt80)
• PTH 148.5 pg/mL (ref 15-65)

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Case 2 cont

• Mg 0.15( 0.7-1.0) mmol/L,

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Case 2 cont.

• Other investigations
• CXR/PFA NAD
• OGD/Colonoscopy NAD
• AUS loss of normal cortical medullary
  differentiation
• MRI brain NAD

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Case 2 cont.

• Treatment
• iv Magnesium 7 g in total
• Vit D2 50 000 iu im
• Magnesium Verla 5 g bd ( 5g equiiv. 5 mmol or
  121.5 mg magnesium)
• One-Alpha 0.5 mcg (alfacalcidol) for 1/52
• Calcichew D3Forte ii od (one tablet 400 IU Vit
  D3, 500 mg Cacarbonate)
• Kay-Cee-L (75 mg KCl per 1 mL)

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25/4 22/7 28/8 13/11 13/11
Ca 1.24 1.72 2.44 2.46
Mg 0.15 0.11 0.89 0.89
K 2.9 2.5 4.4 4.6
25 OH VitaminD 32 35 41 79
Albumin 28 32 40 42
PTH 148 19
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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
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Disorders of Endocrine Glands

• Underactivity with under production of normal
  hormone
• Overactivity with over production of normal
  hormone
• Inappropriate production of hormone not normally
  produced
• Ectopic production of hormone by a non-endocrine
  gland

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Disorders involving the Pituitary Gland
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Hypopituitarism

• Partial or complete deficiency of anterior and/or
  posterior
• pituitary hormones
• Causes
• Pituitary tumours
• Parapituitary tumours e.g. craniopharingioma,
  metasases
• Radiotherapy
• Apoplexy (infarction)
• Infiltration sarcoidosis, histiocytosis x,
  haemochromatosis
• Infections TB, abscess
• Trauma- post head injury
• Genetic syndromes e.g. Kallmanns syndrome, Laron
  dwarfism

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Hypopituitarism- Clinical Manifestations
GH Children growth delay Adults GHD
FSH/LH Delayed puberty Oligo/amenorrhoea Erecile dysfunction testicular atrophy Loss of secondary sex characteristics
ACTH hypoadrenalism
TSH hypothyroidism
Prolactin Failure of lactation
AVP (ADH) Diabetes insipidus
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Hypopituitarism Biochemical investigation

• Basal hormone levels
• LH, FSH, Testo / E2
• TSH and T4
• 9am cortisol
• Prolactin (PRL)
• IGF-1 (marker of GH action)
• Dynamic function tests
• Insulin tolerance test (ITT) for Cortisol and
  GH response
• GnRH test for LH, FSH reserve
• TRH test for TSH reserve (rarely used now)
• Also need to consider imaging pituitary gland
  MRI, CT

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Acromegaly - Excess GH secretion

• Causes
• Pituitary tumour
• Macroadeneoma gt10mm
• Microadenoma lt10mm
• Clinical presentaion
• Pituitary gigantism in childhood
• Acromegalic symptoms
• Increased sweating
• Headaches
• Fatigue/tiredness, joint pains
• Change in shoe size, ring size

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Acromegaly clinical signs

• Facial appearances - characteristic
• Deep voice
• Macroglossia
• Enalarged hands/feet
• Carpal tunnel syndrome

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Biochemical Investigation of Suspected GH Excess

• Oral glucose tolerance test (75g load)
• in acromegaly there is a failure to suppress GH
  to lt 2 mU/L
• IGF-1 usually elevated
• Check other pituitary hormones ( see in Hypopit
  section)
• Imaging of pituitary

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Cushings syndrome - Excess circulating cortisol

• Causes
• Exogenous steroids
• ACTH secreting pituitary tumour
• Ectopic production of ACTH
• Adrenal tumour
• Clinical Features
• Facial appearance moon facies, plethoric
  complexion, acne
• Weigt gain central obesity, buffalo hump
• Thin skin, easy bruising,
• Proximal muscle weakness
• Mood disturbance
• Menstrual disturbance, hirsutism
• Hypertension

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Cushings Syndrome
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Investigation of suspected Cushings syndrome
Does the patient have Cushing syndrome? What
is causing the patients Cushing syndrome?
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Does the Patient have Cushings syndrome?
Out-patient tests Overnight dexamethasone
suppression (1mg at midnight) Normal 9am
cortisol lt 50nmol/l 24 hour urinary free
cortisol In-patient tests Midnight cortisol
looking for loss of cicardian rhythm Low dose
dexamethasone suppression test (0.5mg qds for
48hour) Normal 48hr cortsiol lt 50 nmol/l
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What is the underlying cause of Cushings
syndrome?

• Plasma ACTH level
• ACTH-dependent if non-suppressed or elevated
• - Pituitary
• Ectopic
• ACTH independent if suppressed
• Adrenal
• To differentiate Pitutary ad ectopic causes
• High dose dexamethasosne suppression (2mg qds x
  48hr)
• Pituitary suppresses to lt 50 basal value
• CRH test
• exagerated cortisol and ACTH response in pituiray
  Cushings
• Inferior petrosal sinus sampling pituitary
  imaging

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Hyperprolactinaemia

Condition Example
Physiological Pregnacy, lactation
Idiopathic
Stress venepuncture
Drugs Dopamine agonistse.g Phenothiazines
Chronic liver/renal disease Cirrhosis, CRF
Hypothalamic/pituitary disorders Micro/macroadneoma Stalk compression syndrome
Primary hypothyroidism
PCOS
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Hyperprolactinaemia clinical presentation

• Females
• Oligo/amenorrhoea
• Galatorrhoea
• Infertility
• Reduced libido
• Symptoms relating to pituitary tumour
• Males
• Symptoms relating to pituitary tumour e.g.
  headache, visual disturbance
• Less frequently, reduced libido, infertility,
  galatorrhoea

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Biochemical investigation of Hyperprolactinaemia

• Plasma Prolactin
• -At least two confirmed elvations in plasma
  prolactin
• -Must screen for Macroprolactinaemia ( a high
• mol wt form of circulating prolactin)
• -Macroprolactinaemia is not clinicall significant
• -Prolactin levels gt 5000mU/L are indicative of a
  pituitary adenoma
• Check routine bloods
• -renal and liver function
• -TFTs
• -Pregnancy test (hCG)
• -FSH/LH, E2
• Imaging of pituitary gland if indicated

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What are the commonly measured TFTs?

• Total T4 includes protein bound and Free
  Thyroxine
• Free Thyroxine is the active hormone
• TBG is the main protein binding Thyrxoine
• Increased TBG s seen in pregnancy
• Free T4 (FT4)
• TSH reflects the pituitary response to FT4
  level
• Total T3
• useful in the diagnosis of T3 toxicosis
• - Normal T4 and suppressed TSH

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Patterns of Thyroid Function Tests
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Hypoglycaemia

• Definition plasma glucose lt 2.8mmol/l (blood
  glucose lt 2.2mmol/l)
• Clinically presents with - adrenergic features,
  neuroglycopaenia
• Whipples triad -
• Symptoms signs of hypoglycaemia
• Plasma glucose lt 2.8mmol/l
• Relief of symptoms by glucose intake
  (infusion/oral)

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Hypoglycaemia

• Causes
• Drug therapy - Insulin, Sulphonylurea,
  ?-blockers, Quinine
• Factitious - Insulin, sulphonylureas (healthcare
  workers)
• Fasting Hypoglycaemia
• Insulinoma
• Hepatic failure - gluconeogenesis
• Sepsis, Cardiac failure
• Hypopituitarism, Addisons disease
• Tumour-related hypoglycaemia
• - mesenchymal tumours e.g. fibrosarcoma etc.
• ? Ectopic IGF II by tumour cells
• Autoantibodies - Insulin, Insulin receptor

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Hypoglycaemia
Reactive Hypoglycaemia Idipopathic Early
diabetes Post-gastric surgery
Investigations 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
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Polyuria
Urine output gt 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 Hypokalaemia Hypercalcaemia
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Polyuria

• In clinical practice the most common reason for
  doing a
• water deprivation test is to differetiate between
• Psychogenic polydipsia
• Diabetes Insipidus - central AVP (ADH)
  deficiency
• - nephrogenic
  AVP action on renal tubule
• Water Deprivation test vasopressin
  administration

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Addisons Disease

• Primary adrenal insufficiency
• - differentiate from secondary i.e. ACTH
  deficiency
• - tertiary CRH suppression by exogenous steroids
• Clinically
• Weakness, fatigue, anorexia, wt loss, postural
  hypotension, Coma
• Hyperpigmentation
• - elbows, knees, buccal mucosa, recent scars
  (ACTH levels)

• Causes
• Autoimmune - ? Polyglandular autoimune syndromes
• Infections - TB, fungal infections, HIV
• Metastatic disease - lung, Breast, colon
  (bilateral disease)
• Medications - ketoconazole
• Waterhouse Freidrickson - bilateral adreanl
  haemorrahage (sepsis e.g menigococcus)

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Biochemical abnormalities in Addisons Disease

• Hyponatraemia
• Hyperkalaemia
• Pre-renal failure plasma urea creatinine
• ? Hypercalcaemia
• Abnormal TFTs - TSH, T4 (hypothyroid
  picture)
• - May be a transient picture
• NB treat hypoadrenalism before giving L-T4

Acute presentation Take blood sample for plasma
Cortisol and ACTH levels before steroid
administration Plasma Cortisol Plasma
ACTH NB Dexamethasone does not interfere with
cortisol assay
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Biochemical Diagnosis of Addisons disease

• Chronic Presentation
• Short synacthen test
• does not differentiate between primary and
  secondary
• -Synacthen 250 µg IM
• 0, 30 and 60 min plasma cortisol
• 30 min Plamsa Cortisol gt 550 nmol/L
• Long synacthen test
• Adrenal antibodies

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Biochemical paraneoplastic syndromes

• Tumours of specific endocine glands e.g.
  insulinoma, pituitary etc.
• Hypercalcaemia of malignancy
• Syndrome of inappropriate antidiuresis (SIAD) -
  hyponatraemia
• Cushings syndrome
• Tumour-induced hypoglycamia
• Tumour-induced osteomalacia - mesenchymal
  tumours (hemangiopericytoma)
• Normal Ca, PO4, 1,25 (OH)2 Vit D
• ??Renal phosphate wasting
• Carcinoid syndrome - facial flushing, diarrhoea,
  brochospasm
• Laboratory diagnosis - urinary 5 hydroxyindole
  actetic acid (5HIAA)

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Case 1 Hx

• 35 yr old male
• Hx EBV infection 8 weeks previously
• No medical or family hx of note otherwise
• Not on regular medication
• C/O vague/nonspecific symtoms, fatigue
• GP performed routine blood tests including TFTs

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Case 1 TFTs

• TT4 223 (63-142)
• TSH 4.87
• Repeated 2-3 weeks later
• TT4 171
• TSH 2.89

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Case 1 TFTs (cont)

• FT4 51.3 (9-24)
• T3 3.5 (0.8-2.5)
• Biochemical Hyperthyroidism

• No clinical features of thyrotoxicosis
• No biochemical evidence of heterophile ab
  interference
• No family hx of thyroid dx

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Case 1 Differential Dx

• TSHoma
• Thyroid hormone resistance (RTH) - Refetoffs
  syndrome
• FDH rare
• Heterophile abs
• MRI scan of pituitary Macroadenoma - TSHoma

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Case 2 History

• Phone call from a GP regarding TFTs
• 54 yr old male vague hx fatigue
• T4 40 (69-141)
• TSH 1.53
• Sample recovered and tested for
• FT4 5.7 (9-24)
• TBG 25 (13-24)
• A large clot was noted in serum
• R/O artefact repeat investigation with

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Case 2 Repeat TFTs

• TT4 44
• FT4 4.9
• TSH 1.2
• Cortisol 130 (random am)
• Testo 10.5 (8.7 33.0)
• LH 2.4
• FSH 6.3
• GH lt 1.0
• IGF-1 lt 25
• PRL 419 (70-413)

Central Hypothyroidism Referred to endocrine
service SJH
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Case 2 Endocrine assessment

• Stimulation testing (ITT)
• Achieved hypoglcaemia
• GH deficient
• ACTH/Cortisol deficient
• Centrally hypothyroid
• MRI scan empty sella ? cause

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Case 3 Background

• 23 yr old male
• Hx Migraine and fatigue
• GP performed TFTs
• TT4 43
• TSH 2.89
• Biochem Registrar signing out - ? Hypothyroid
• - Put on some additional test
• FT4 5.8 (9-24)

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Case 3 Endocrine tests

• More additional tests after discussion with GP
• Cortisol 97 (244-727) but NB diurnal variation
• FSH 2.7 (1.0-10.5)
• LH 2.2 (1.0 6.0)
• Testo 1.3 (8.7-33)
• Prolactin 4490 (70-413)
• Post fractionation Prolactin (PFP) 3960

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Case 3 Diagnosis

• Biochemical Dx
• Hypothyoid
• Hypogonadal
• Hypocortisolaemic
• Hyperprolactinaemic
• Hypopituitarism
• MRI scan Macroadenoma - ? Macroprolactinoma

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Case 4 background

• 43 yr old female
• Hx Spina Bifida (wheel chair bound)
• Currently in Cheshire Home
• 4/52 hx malaise
• Admitted to St Elsewhere
• Atonic Bladder
• Renal impairement
• GP to monitor U/Es

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Case 4

• Result brought to attention of Consultnat Chem
  Path
• Hypernatraemia ? Cause

5/5 6/5 12/5
Na 165 162
K 3.6 3.0
Urea 14.2 6.9
Crea 167 133
POsmo 352
UOsmo 410 222
Gluc 13.6 9.7
fasting
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Case 4 Dx?

• Results suggestive of
• DI
• DM

Paired urine and plasma osmolality are very
useful in directing management of
-hypernatraemia -hyponatraemia
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24 yr old male Unwell Hx of admissions with
hypoNa Na 121 K 5.5 Urea 9.3 Crea 118 T4 83 TSH
4.97 Cortisol 52 ACTH 1122