chem Flashcards
osmolality equation
2(Na +K) + glucose + urea
what is the difference between osmolality and osmolarity
osmolality = /kg, more accurate
osmolarity = /litre, more practical
what is the biggest contributor to osmolality
sodium
what is osmolality gap
difference between calculated and measured osmolality, due to things not included in calc (sugars, alcohol)
what is pseudohyponatraemia
reduced Na, normal/high osmolality
HYPOvolaemic HYPOnatraemia with LOW urinary sodium
extra renal loss (vomiting, diarrhoea, burns)
HYPOvolaemic HYPOnatraemia with RAISED urinary sodium
renal loss (diuretics, renal loss)
HYPERvolaemic HYPOnatraemia with LOW urinary sodium
CCF, cirrhosis, nephrotic syndrome
HYPERvolaemic HYPOnatraemia with RAISED urinary sodium
CKD
EUvolaemic HYPOnatraemia with LOW urinary sodium
psychogenic polydipsia
EUvolaemic HYPOnatraemia with RAISED urinary sodium
hypothyroid, SIADH, adrenal insufficiency
HYPOvolaemic HYPERnatraemia
osmotic diuresis, diarrhoea, burns
HYPERvolaemic HYPERnatraemia
hyperaldosteronism
hypertonic 3% saline
hypernatraemia management
oral water intake
slow IV 5% dextrose
causes of central diabetes insipidus
pituitary surgery, irradiation, tumour
central diabetes insipidus management
desmopressin
causes of nephrogenic diabetes insipidus
electrolyte disturbance (hypokalaemia, hyperglycaemia)
drugs (lithium)
nephrogenic diabetes insipidus management
thaizides
diabetes insipidus investigations
glucose - exclude DM
K - exclude hypo
Ca - exclude hyper
water deprivation test
hypokalaemia features
muscle weakness, cramps, hypotonia
causes of hypokalaemia - increased loss
GI loss (d+v, high output stoma)
renal loss (conn’s, diuretics)
causes of hypokalaemia - increased cellular influx
insulin
beta agonists
refeeding syndrome
metabolic alkalosis
hypokalaemia investigations
Mg - correct if low
if raised BP, aldosterone: renin ratio
hypokalaemia management
mild-moderate (2.5-3.5) - oral sando K
severe (<2.5) IV replacement, continuous ECg
hyperkalaemia ECG features
tall tented T waves, small p, wide QRS
hyperkalaemia causes - artifact
haemolysis
hyperkalaemia causes - iatrogenic
massive blood transfusion
excess supplmentation
hyperkalaemia - reduced excretion
renal disease
addison’s
drugs (ACEi, ARB, K sparing diuretics)
hyperkalaemia - increased cellular release
tissue breakdown
hyperkalaemia investigations
renal function
cortisol/ short ACTHen test
CK
hyperkalaemia management
if >6.5 or ECG changes
IV calcium gluconate
IV insulin w/ dextrose
what hormone has the opposite affect to PTH
calcitonin
hypocalcaemia features
peri-oral paraesthesia, long QT, spasm, tetany
hypocalcaemia causes
osteomalacia
hypoparathyroidism
hypocalcaemia investigations
ECG
bloods (Mg, phosphate, PTH, ALP)
dexa
hypocalcaemia management
mild (>1.9) - oral calcium/ vit D supplement
severe - IV calcium gluconate
hypercalcaemia features
stones, bones, abdo groins, psychic moans
hypercalcaemia causes (raised PTH)
primary/ tertiary hyperparathyroidism, late stage CKD
if primary hyper, suspect MEN1/2a
hypercalcaemia causes (low PTH)
malignancy
hyperthyroid
hypoadrenal
sarcoidosis
thiazides
hypercalcaemia Ix
myeloma screen
TFTs, cortisol
hypercalcaemia management
fluids
acute - IV normal saline
medical - bisphosphonates (if malignancy)
surgical - parathyroidectomy
isolated raised ALP
paget’s disease
alcoholic hepatitis AST:ALT ratio
> 2
viral hepatitis AST:ALT ratio
<1
hypothyroid autoimmune causes
primary atrophic (no goitre)
hashimoto’s (goitre + anti-TPO/TG)
hypothyroid other causes (not autoimmune)
iodine deficiency
surgery/ radioactive ablation
drugs - amiodarone, lithium, carbimazole
myxoedema coma management
IV liothyronine
what is sick euthyroid
in severe illness
reduced T3, T4
initially increased TSH, then reduced
syndrome with increased TSH but normal T3/4
subclinical hypothyroidism
what antibody is associated with increased risk of hypothyroid in subclinical hypothyroid
anti-TPO
causes of hyperthyroid
graves
de quervain’s thyroiditis
thyroid adenoma
amiodarone
toxic multinodular goitre
post-partum
focal lesions on thyroid reuptake scan
adenoma
multiple patchy lesions on thyroid reuptake scan
toxic goitre
generalised increased uptake on thyroid reuptake scan
graves
cold thyroid on reuptake scan
de quervain’s
medical management of hyperthyroid
carbimazole or propylthiouracil
beta blockers for AF/ palpitations
lugol’s iodine - make pt euthyroid for surgery
radio-iodine - risk permanent hypo
where is the pituitary gland
sella turcica just below optic chiasm
malignant causes of hypopituitarism
pituitary adenoma
craniopharyngioma
infective causes of hypopituitarism
TB
syphilis
infiltrative causes of hypopituitarism
sarcoid
lymphoma
iinfarct causes of hypopituitarism
sheehan’s
apoplexy
tertiary causes of hypopituitarism
kallman’s
prader-willi
what is combined pituitary function test
give GnRH, TRH and insulin, measure GH, cortisol, TSH, LH, FSH and prolactin every 30 mins for 2 hrs
hypopituitarism management
hydrocortisone
thyroxine
oestrogen/ testosterone
effects of pituitary macroadenoma
usually non-functional
bitemporal hemianopia
effects of pituitary microadenoma
GH or prolactin secreting
prolactin –> galactorrhoea, gynaecomastia, oligo/amennorhoea, loss of libido, impotence
GH –> acromegaly, organomegaly, heart failure sx, htn, dm, carpal tunnel
acromegaly Ix
glucose tolerance test
plasma IGF-1
pituitary adenoma management
octreotide (somatostatin analogue)
cabergoline or bromocriptine (dopamine agonist)
pegvisomant (Gh antagonist)
surgery - trans-sphenoidal debulking
most common type of thyroid tumour
papillary
second most common thyroid tumour
follicular
medullary thyroid cancer features
c-cells that produce calcitonin
linked to men2
5% of thyroid cancers
type of thyroid cancer linked with hashimoto’s
lymphoma
anaplastic thyroid cancer features
elderly patients, poor prognosis
undifferentiated
management of papillary/ follicular thyroid cancer
surgery +/- radioactive iodine
replace thyroxine to completely supress TSH
monitor thyroglobulin levels
what is produced in the glomerulosa of adrenals
mineralocorticoids (aldosterone)
what is produced in the fasciculata of adrenals
glucocorticoids (cortisol)
what is produced in reticularis of adrenals
sex hormones
what is produced in adrenal medulla
catecholamines
most common cause of addisons in the UK
autoimmune
most common cause of addison’s worldwide
TB
addison’s features
postural drop, fatigue
weight loss, anorexia
vomiting, salt craving
skin/ mucosal pigmentation
addison’s ix
9am cortisol >350 excludes hypoadrenalism
synACTHen test - if cortisol rises –> secondary cause (pituitary), if not then primary
hyponatraemia, hyperkalaemia
features of addisonian crisis
hypotension
hypovolaemia
hypoglycaemia
addisons management
hydrocortisone (double dose if unwell)
fludrocortisone
what is schmidt’s syndrome
simultaneous hypoadrenalism and hypothyroid
cushings causes
primary - adrenal malignancy
secondary - pituitary adenoma, ectopic/ paraneoplastic
iatrogenic (exogenous steroids)
cushings ix
low dose dexmethasone suppression test - confirm syndrome
high dose dexamethasone suppression test - syndrome vs disease (adenoma)
cushings imaging
CT CAP/ adrenals
MRI pituitary
ectopic cause cushings management
ketoconazole, metyrapone, mifepristone
primary cushings management
adrenalectomy +/- steroid replacement
CKD electrolytes
reduced NA, raised K, raised urea
addisons electrolytes
reduced Na, raised K, reduced glucose
ethanol electrolytes
reduced Na, raised osmolality
conn’s syndrome electrolytes
raised Na, reduced K
D/V electrolytes
reduced Na, reduced osmolality, reduced urine osmolality
insulin OD electrolytes
reduced K, raised pH
bartter syndrome electrolytes
reduced K, raised pH, raised urinary calcium, hypotension
renal tubular acidosis electrolytes
reduced K, reduced pH
causes of RAISED anion gap metabolic ACIDOSIS
methanol/metformin
uraemia
DKA
iron
lactate
ethanol
salicyte
causes of NORMAL anion gap metabolic ACIDOSIS
diarrhoea
addison’s
renal tubular acidosis
kallman’s syndrome features
hypogonadotropic hypogonadism
reduced LH, FSH
anosmia
what is secondary hypoaldosteronism
pituitary defect –> reduced ACTH –> reduced aldosterone, cortisol
familial benign hypercalcaemia biochemistry
raised PTH, raised Ca, reduced urinary calcium
most common cause of secondary hyperparathyroidism
chronic renal failure
what is pseudohypoparathyroid
PTH resistance
raised PTH, raised phosphate, reduced Ca
causes of raised serum amylase
pancreatitis
mumps
ferritin in IDA
reduced
ferritin in anaemia of chronic disease
increased
ferritin in thalasaemia
normal
causes of bence-jones proteins
multiple myeloma
amyloid light chain amyloidosis
cause of low caeruloplasmin
Wilson’s
causes of raised CEA
colorectal cancer, gastric cancer, pancreatic cancer
what is raised aFP associated with
hepatocellular carcinoma
vitamin B12 deficiency
megaolblastic anaemia
hypersegmented neutrophils
can get subacute cord degeneration - ataxia, progressive limb weakness, babinski sign positive
what does vitamin E deficiency cause
haemolytic anaemia
spino-cerebellar neuropathy - ataxia, areflexia
what does vitamin B6 deficiency cause
sideroblastic anaemia
seborrhoeic dermatitis
what can cause b6 deficiency
TB treatment (Isonazid)
what does B1 deficiency cause
wernicke’s encephalopathy, korsakoff’s syndrome
beri-beri wet - like heart failure
dry - ascending nervous system impairment
what does vitamin A deficiency cause
night blindness, conjunctival bitot’s spots
predisposed to measles, diarrhoea
what does vitamin B2 deficiency cause
angular stomatitis, glossitis and/or corneal ulceration
features of homocystinuria
very fair skin, brittle hair
developmental delay
convulsions, skeletal abnormalities, thrombotic episodes
what do you supplement homocystinuria pts with
B6
PKU features
fair hair, developmental delay, severely impaired IQ, eczema, seizures
von gierke’s syndrome features
hypoglycaemia
hepatomegaly, enlarged kidneys
maple syrup urine disease features
toxic encephalopathy (lethargy, poor feeding, hypotonia, seizures)
sweet odour, sweaty feet
fabry’s syndrome features
developmental delay with dysmorphia
cherry red spots
deafness, blindness, movement disorders
SCAD deficiency features
failure to thrive, hypotonia, metabolic acidosis, hyperglycaemia
galactosaemia features
vomiting, jaundice, hepatomegaly after milk ingestion
toxicity features of phenytoin
hypotension
heart block
ventricular arrhythmias
ataxia
toxicity features of lithium
D+V, coarse tremor, dysarthria
convulsions
renal failure
toxicity features of gentamicin
deafness, renal failure, balance/ vision issues
toxicity potentiated by kidney function, use of vancomycin
toxicity features of digoxin
tiredness, blurred vision, nausea, abdo pain, confusion
prolonged PR, bradycardia
toxicity features of theophylline
nausea, diarrhoea
tachycardia, arrhythmias, headaches, seizures
potentiated by erythromycin, ciprofloxacin
toxicity features of procainamide
fever, rash
agranulocytosis
toxicity features of methotrexate
ulcerative stomatitis
leukocytopenia
pulmonary fibrosis
toxicity features of carbamezapine
headaches, ataxia, abdo pain
SIADH
aplastic anaemia
toxicity features of cyclosporine
acute renal failure
what electrolyte abnormality does metabolic alkalosis cause
HYPOkalaemia
acute renal failure biochemical picture
HYPERkalaemia
metabolic acidosis
what electrolyte abnormality can carbamezapine cause
hyponatraemia
PTH resistance with low calcium
pseudohypoparathyroidism
PTH resistance with normal calcium
pseudopseudohypoparathyroidism
test for thiamine deficiency
red blood cell transketolase activity
test for B2 (riboflavin) deficiency
red blood cell glutathione reductase
riboflavin deficiency manifestation
glossitis
mouth ulceration
dry skin
test for B6 (pyridoxine) deficiency
red cell aspartate aminotransferase
B6 deficiency manifestation
seborrhoeic dermatitis like rash
angular chellitis
confusion, neuropathy
can be cause by isoniazid
conn’s syndrome picture
hypertension
hypokalaemia
metabolic alkalosis
gout vs pseudogout birefringence
gout = negatively birefringent
pseudogout = positive birefringence
gout exacerbating factors
alcohol
aspirin
thiazide diuretics
chemo
acute gout management
NSAIDS, colchicine
long term gout management
allopurinol
causes of metabolic acidosis with raised anion gap
methanol
uraemia
DKA
propylene glycol
isoniazid
lactic acidosis (shock, infection , ischaemia)
ethylene glycol
salicylates
anion gap calculation
Na + K - HCO3 - Cl
chronic renal failure phosphate
RAISED
which bone cells produce ALP
osteoblasts
cataracts, poor feeding, lethargy, conjugated hyperbilirubinaemia with hepatomegaly and reducing sugars in urine after starting milk
galactosaemia
alcohol abuse and chronic pancreatitis can cause reduced absorption of fat soluble vitamins and as such cause
osteomalacia
reduced absorption of dietary vitamin D causes what bloods
LOW 25-hydroxy-cholecalciferol
HIGH 1,25-dihydroxy-cholecalciferol
which vitamin D metabolite is produced following hydroxylation in the kidney stimulated by PTH?
1,25-dihydroxy-cholecalciferol
causes of raised ALP
liver related (cholestasis, hepatitis, fatty liver, tumour)
drugs (phenytoin, erythromycin, carbamezapine, verapamil)
bone disease (paget’s, renal osteodystrophy, fracture)
vitamin D deficiency, secondary hyperparathyroidism
malignancy (bone metastases, breast, colon, Hodgkin’s lymphoma)
vitamin D3 deficiency (Pellagra)
dementia
diarrhoea
dermatitis
death
symptoms of vitamin E deficiency
haemolytic anaemia
spinocerebellar degeneration
peripheral neuropathy
list the fat soluble vitamins
A
D
E
K
how many half lives does a drug take to reach steady state
4-5
hypoketotic hypoglycaemia with hepatomegaly and cardiomyopathy
MCADD
pituitary failure leads to lack of
ACTH
TSH
biochemical cause of acute pancreatitis
hypercalcaemia
drugs that lead to reduced serum K concentration
calcium resonium
insulin
salbutamol
sodium bicarbonate
which toponin is the best marker of MI
Troponin I
best enzyme marker to detect reinfarction of heart
CK MB
what is a cause of facitious hypoglycaemia other than exogenous insulin
sulfonylureas
cyanide poisoning first line
hydroxocobalamin
MEN1 features
Pituitary adenoma
Parathyroid hyperplasia
Pancreatic tumours
(3 Ps)
MEN 2A features
Parathyroid hyperplasia
Medullary thyroid carcinoma
Phaeochromocytoma
MEN 2B features
Medullary thyroid carcinoma
Phaeochromocytoma
marfanoid body habitus
mucosal neuromas
inheritance of MEN disorders
autosomal dominant
gilbert’s inheritance
autosomal recessive
enlarged orange tonsils, with hepatomegaly, splenomegaly
tangier disease
what can’t you give with azathioprine in pts with TPMT deficiency
allopurinol
term for increased bone density
osteosclerosis
looser zones
osteomalacia
which cholesterol transport channel does ezetimibe target
NPC 1L1
cardiac protection in hyperkalaemia
calcium gluconate
how to determine if it is a true hyponatraemia
serum osmolality
where are bile acids reabsorbed
terminal ileum
which enzyme has reduced activity in Gilbert’s
UDP glucuronyl transferase
rickets x ray findings
widened epiphysis at wrists
bowed legs
allopurinol MOA
xanthine oxidase inhibition
in sarcoidosis, granulomatous tissue can produce which enzyme to lead to hypecalcaemia
1-alpha hydroxylase
ApoE4 gives increased risk of developing what
alzheimers
what can rapid correction of hyponatraemia cause
central pontine myelinolysis
central pontine myelinolysis symptoms
lethargy, issues speaking, swallowing, walking
condition where there is almost complete failure of PCT to reabsorb molecules
fanconi syndrome
causes of fanconi syndrome
congenital
wilson’s disease
treatracyclines
MM
lead poisoning
