Clinical Chemistry Flashcards
What are the causes of HYPERthyroidism?
- Autoimmune- Grave’s disease
- Thyroid nodules
- Chemical toxicity eg. Amiodarone
What are the clinical signs of HYPERthyroidism?
Increased metabolic rate: Diarrhoea, weight loss anxiety
Increased sympathetic drive: Sweating, tachycardia, tremor
Goitre
Thyroid acropachy
Exophthalmos
Lid retraction
Pretibial myxoedema
What is thyroid acropatchy?
Extreme mannifestation of hyperthyroidism
Clubbing
Painful finger and toe swelling
Periosteal bone reaction
What is pretibial myxoedema?
Oedematous swelling above the lateral malleoli
Due to hyaluronic acid deposition
Discoloured skin
What is exophthalmos
Anterior bulging of the eye out of the orbit
What are the treatments for HYPERTHYROIDISM?
- Thionamides eg. Carbimazole which inhibit thyroid peroxidase
- Radioactive iodine
- Thyroidectomy
What are the causes of HYPOTHYROIDISM?
- Autoimmune- Hashimoto’s
- Iodine deficiency
- Pituitary disease
What are the clinical signs of HYPOthyroidism?
Weight gain Dry skin and hair Hoarse voice Bradycardia Constipation Tiredness Round puffy face Depression
What are the treatments for HYPOthyroidism?
- Levothyroxine - aim for normal TSH, check after 4 weeks
Which hormones are produced by the anterior pituitary?
Growth Hormone Thyroid Stimulating Hormone Prolactin FSH and LH ACTH
Which hormones are released by the posterior pituitary?
Oxytocin
ADH
What are the clinical features of a prolactinoma?
Galactorrhoea (spontaneous milk production)
Amenorrhoea
Loss of axillary/pubic hair
What causes a prolactinoma?
Pituitary adenoma
What is the treatment for a prolactinoma?
Dopamine agonists eg. Bromocriptine, Cabergoline
as dopamine inhibits prolactin synthesis
Rare side effects = manic symptoms
What are the clinical features of acromegaly?
Large hands/ feet
Wide nose
Sweating and headache
Cardiomyopathy, hypertension, diabetes
What are the treatments for acromegaly?
- Trans-sphenoidal surgery 1st line
- Somatostatin analogues eg. Lanreotide, Ocreotide which are growth hormone inhibiting hormone
- Pegvisomant if resistant
What is the role of ADH?
Acts on renal collecting ducts, reabsorption of water via aquaporins
Makes urine more concentrated
What happens in diabetes insipidus?
Too LITTLE ADH produced due to posterior pituitary damage
Large volume urine
Blood more concentrated
Causes hypernatraemia, thirst, polyuria
What is the treatment for diabetes insipidus?
Desmopressin (ADH analogue)
What happens in SIADH?
Too much ADH produced, causes low urine output and increased blood volume so hyponatraemia
What are the causes of SIADH?
Head injury
Malignancy- lung small cell, pancreas, prostate
Infection - Pneumonia, meningitis
Medication- Diuretics, AEDs, SSRIs
What are the treatments for SIADH?
- Volume restriction
- Vasopressin antagonists (Vaptans)
- Demeclocycline
What is Addison’s disease?
Primary adrenal insufficiency
Leads to decreased adrenalin, cortisol and aldosterone
What are the causes of HYPERnatraemia?
Volume loss- diarrhoea, vomit, burns Diabetes insipidus Primary hyperaldosteronism (Conn's) Iatrogenic- incorrect fluid replacement Osmotic diuresis
How is hypernatraemia managed?
- Oral fluid
- Glucose 5% IV 1:6
- Saline 0.9% if volume depleted
What are the causes of hyponatraemia?
IF DEHYRDRATED:
- Loss via kidneys: Addison’s excess diuretics, renal failure, osmotic diuresis
- Loss elsewhere: diarrhoea, vomit, burns, fistulae, bowel obstruction, CF, trauma
IF NOT DEHYDRATED:
- Cardiac failure, renal failure, liver cirrhosis, nephrotic syndrome
- SIADH, volume overload, severe hypothyroidism
What is the treatment for hyponatraemia?
Correct sodium/ water loss:
- Fluid restrict if asymptomatic
- Saline 0.9% slowly
- Vaptans- vasopressor receptor antagonists- promote water loss without sodium loss
What is the risk if saline is given too quickly to correct Hyponatraemia?
Central Pontine Myelinolysis
Irreversible and often fatal pontine demyelination seen in rapid correction of low sodium.
What is normal plasma osmolality?
275-295mOsm/Kg
Which foods are high in potassium?
Banana Prune juice Papaya Raisins Mango Orange Pear
After a potassium load, which hormones are released?
Insulin Aldosterone Catecholamines (adrenalin, noradrenalin, dopamine)
How do insulin and catecholamines impact on potassium levels?
IF potassium INCREASES, insulin and catecholamines cause INCREASED uptake of potassium to cells (skeletal muscle, liver and adipose)
How does aldosterone impact on potassium levels?
It INCREASES the amount of potassium excreted renally
What are the potassium levels in metabolic ACIDOSIS?
HYPERkalaemic
What are the potassium levels in metabolic ALKALOSIS?
HYPOKalaemic
What ECG changes are seen in HYPERKalaemia?
- Tall tented T waves
- Wide QRS complex
- Flattened P wave
What are the concerning signs/ symptoms in HYPERkalaemia?
Fast irregular pulse
Palpitations
Chest pain
Light headedness
What are the causes of HYPERkalaemia?
INCREASED POTASSIUM INTAKE: oral or IV therapy
REDUCED POTASSIUM EXCRETION: CKD, Addison’s, Tubular defects
ALTERED DISTRIBUTION: Metabolic acidosis
Rhabdomyolysis, crush injury, diabetes
DRUGS: ACEIS, ARBS, Spironalactone
Which blood bottle should be collected first; yellow or purple?
Yellow
Then Purple
How should HYPERkalaemia be treated?
- Cardioprotection: ECG monitor, Calcium gluconate
- Potassium removal: Furosemide, Ion exchange resins, dialysis
- Potassium redistribution: Insulin, glucose, salbutamol nebuliser, bicarbonate
What are the consequences of Hyperkalaemia?
Weakness Paralysis Nausea and vomit Ileus Arrhythmias
What are the causes of HYPOKalaemia?
- GI LOSSES: Diarrhoea, Fistula, Pyloric stenosis
- RENAL LOSSES: Loop diuretics, Mineral corticoid excess eg. Cushings, Conn’s
- REDISTRIBUTION: Salbutamol, Metabolic Alkalosis
What are the ECG changes in HYPOKalaemia?
Flat T wave/ T wave inversion
Prominent P waves and U waves
ST depression
Prolonger PR interval
How is HYPOKalaemia treated?
- Oral potassium eg. Sando k
2. IV potassium
What is the role of parathyroid hormone?
Increases serum calcium and Decreases serum phosphate
Increases osteoclast activity
Increases renal production of Vit D3
What is the role of calcitonin?
Decreases serum calcium
How does magnesium impact PTH?
Magnesium REDUCES the release of PTH
Which protein does calcium bind in blood?
Albumin (40% of calcium is bound, rest is free)
What are the signs/ symptoms of hypocalcaemia?
SPASMODIC: S- Spasms P- Perioral paraesthesia A- Anxious and irritable S- Seizures M- Muscle tone increased -> wheeze and colic O- Orientation impaired D- Dermatitis I- Impetigo C- Corner of mouth twitches Chvostek sign
What are the causes of LOW calcium with HIGH phosphate?
- Hypoparathyroidism
- CKD
- Magnesium deficiency
- Pseudohypoparathyroidism
What are the causes of LOW calcium with NORMAL/ LOW phosphate?
- Vitamin D deficiency
- Osteomalacia (adult version of rickets)
- Acute pancreatitis
- Respiratory alkalosis
- Over hydration
What are the signs of Hypercalcaemia?
Bones, stones, moans, groans
Abdominal pain Vomiting Depression Hypertension Kidney stones Weight loss Ectopic calcification
What are the commonest causes of hypercalcaemia?
Malignancy- bone mets, myeloma
Hyperparathyroidism
What suggests that malignancy has caused a Hypercalcaemia?
Raised ALP
Low albumin, chloride and potassium
Raised phosphate
Alkalosis
What suggests that hyperparathyroidism has caused a hypercalcaemia?
Raised PTH
What are the less common causes of Hypercalcaemia?
Sarcoidosis
Vitamin D excess
Lithuim
Tertiary hyperparathyroidism
How is HYPERCalcaemia treated?
- Correct dehydration 0.9% saline
- Bisphosphonates- inhibit osteoclasts eg. Zoledronate
- Calcitonin
What is the triad that makes up nephrotic syndrome?
- Proteinuria
- Oedema
- Hypoalbuminaemia
What is an insulinoma?
Benign tumour of pancreatic islet cells; presents with hypoglycaemia when fasting.
What will the blood results be of a patient with an insulinoma?
Raised insulin levels when fasting
Glucose below 2.5
Raised C-Peptide
What is a Phaeochromocytoma?
Adrenal medulla tumour, producing catcholamines
10% malignant, 10% familial, 10% bilateral
How does a Phaeochromocytoma present?
Sweating Episodic headaches Tachycardia Pallor Anxiety Hypertension
What is normal serum phosphate?
0.8- 1.5
What are the causes of hypophosphataemia?
Vitamin D deficiency
Alcohol withdrawal
Refeeding syndrome
Primary hyperparathyroidism
What is the most common cause of hyperphosphataemia?
CKD
When should Conn’s (Primary Hyperaldosteronism) be expected?
- Hypertension WITH hypokalaemia
- Hypertension despite 3 ant hypertensives
- Hypetension in <40yrs female
What is the most common cause of Cushing’s?
Excess steroid use (Cushing’s syndrome)
What is the second most common cause of Cushing’s?
Pituitary adenoma (Cushing’s disease)
How does Addison’s affect Na, K, glucose levels?
Low sodium
High potassium
Low glucose
What are the causes of hypoyglycaemia in diabetics?
- Insulin use
- Sulfonylureas (Glicazide)
- Missed meal, excess insulin dose, increased activity
What are the causes of hypoyglycaemia in non diabetics?
EXPLAIN: Ex- Exogenous drugs: ACEIs, B Blockers, Alcohol, Aspirin overdose P- Pituitary insufficiency L- Liver failure A- Addisons I- Insulinoma N- Neoplasms
What is Whipple’s Triad (Hypoglycaemia)?
- Low blood glucose
- Symptoms and signs of hypogylcaemia
- Symptoms relieved when blood glucose rises
Which CAUSES of hypoglycaemia will have low insulin, and raised ketones?
Alcohol
Addison’s
Pituitary insufficiency
Which CAUSE of hypoglycaemia will have raised insulin and C peptide on fasting?
Insulinoma
What is the treatment for hypogylcaemia?
If conscious- orange juice
If conscious but uncooperative- glucogel on gums
If unconscious- IV glucose, IM glucagon
Long acting carbohydrate once recovered
What are the 2 main types of hyperglycaemia and which patients do they affect?
- Diabetic ketoacidosis- Mainly type 1
2. Hyperglycaemic hyperosmolar state- Type 2
What 3 criteria are present to diagnose DKA?
- Hyperglycaemia
- High ketones (blood/urine)
- Acidosis
What are the symptoms of DKA?
Drowsiness
Vomitting
Dehydration
What is the treatment for DKA?
- Fluids
- Insulin
Keep checking VBG (pH, Bicarbonate, potassium)
How does Hyperglycaemic Hyperosmolar state differ to DKA?
HHS:
- Glucose >30
- no acidosis
- no excess ketones
- Type 2 diabetics
- less sudden onset
What is the WHO criteria for diagnosing diabetes with regards to HbA1c?
> 48mmol.L
6.5%
How does type 1 diabetes usually present?
Polyuria
Polydispia
Weight loss
Ketosis
How does Type 2 diabetes usually present?
Often asymptomatic
Complications such as MI
What is metabolic syndrome?
Obesity plus 2 of:
- Hypertension
- Raised triglycerides
- Reduced HDL cholesterol
- Diabetes/ high glucose
Which diabetic drug is a Biguanide?
Metformin
What are the side effects of Metformin?
Nausea
Diarrhoea
Abdominal pain
NOT HYPOGLYCAEMIA
Which diabetic drug is associated with weight gain?
Glicazide (sulfonylurea)
Which diabetic drugs are associated with hypoglycaemia?
Glicazide (sulfonylurea)
Glitazone
Which diabetic drug is associated with raised LFTs?
Glitazone
What are the most common causes of hyperkalaemia?
CKD
Metabolic acidosis
What blood results are needed to diagnose Diabetes mellitus?
- HbA1c >48mmol/l
- Fasting glucose >7mmol/L
- Random blood glucose >11mmol/l
What can trigger diabetic ketoacidosis?
Infection
Stress
Pancreatitis
Non compliance with insulin