Chemical Pathology Flashcards
what is the enzyme missing in lesch nyhan
HGPRT
How can one categorise the causes of a raised urate (in gout)
Increased production and decreased clearance
P: myeloproliferative, lymphoproliferative, chronic HA
C: drugs(aspirin and thiazides, lead) CKD or barterrs, downs syndrome.
what is high CRP a risk factor for
cardio problems
what can be broken down to make amino acids
albumin
high fluid intake as a baby can be a risk factor for what
NEC
What is the difference between osmolality and osmolarity
LAL is in kg
LAR is in litres
they are very similar but the difference is known as the osmolar gap.
how do you calculate the osmolarity
2(sodium + potassium) + urea + glucose
normal osmolarity? what does it help diagnose
serum = 275-295 it is used to diagnose SIADH
At what point should you treat the hyponatraemia rather than the underlying cause?
when drops below 125.
What hapens when sodium falls?
N+v - 136
confusion - 131
seizures - pulmonary odema (non cardio) - 125
coma - 117
What is TURP syndrome
water is absorbed through damaged prostate and causes hypoonatraemia
How do you differentiate true hyponatraemia from other causes?
osmolality.
HIGH - glucose/mantiol or infusion
NORMAL - spurious, drip arm sample, paraproteinaemia/hyperlipidaemia
how do you diagnose Adrenal insufficiency
ADDISONS DISEASE - 85%(but not so in the rest of the world) (automimmune)
true hyponatraemia with euvolemia and therefore high urinary sodium (>20)
HIGH POTASSIUM
other causes of adrenal insufficiency include:
TB and other infections
anything interfering with hypothamic axis to prevent release of CRH
SHORT SYNACTHen test to diagnose. there will be no rise in cortisol seen
How do you diagnose SIADH
urine osmolarity is high but serum is low as it is a TRUE hyponatraemia
it is a diagnosis of exclusion
4 causes of SIADH
brain insult
lung pathology
malignancy
drugs - SSRI, carbamazepine, opiates.
What happens with rapid correction of HYPERnatraemia
cerebral odema
occurs in ITU patients
sx include:
thirst confusion, ataxia,
What happens with rapid correction of HYPERnatraemia >148mmol/l
cerebral odema
occurs in ITU patients
sx include:
thirst confusion, ataxia, seizures, coma.
What would you see on results of psychogenic polydipsia
nothing abnormal, merely symptoms of dry mouth and thirst. often accompied by psychological disease such as schizophrenia
What is the normal range of potassium
3.5-5.5
What causes tall tented t waves
hyperkalaemia
in what way are potassium and hydrogen linked?
every time you drop 0.1 in pH your potassium will go up by 0.7
they work in opposites.
What are the causes of hypokalaemia?
ANYTHING WHICH Increases LEVEL OF SODIUM REACHING THE DISTAL NEPHRON
GI loss
Renal Loss - high aldosterone, osmotic diuresis - diabetes.
redistribution into cells - insulin causes entry into vcells as do beta agonsists and an alkalosis
rare causes - renal tubular acidosis
barterr
gitelman
How do you diagnose conns
primary hyperaldosteronism
renin aldosterone ratio.
Renin should be low
When you are acidotic you are____kalaemic
HYPER
Which tranporter is defective in barrters sydrome
triple (permanent frusemide
which transporter is blocked in gitelman syndrome
NaCl like having a permanent thiazide diuretic
What are the causes of hyperkalaemia?
TRANSCELLULAR MOVEMENT
acidosis
low insulin - DKA
tissue damage - crush injury or haemolysis for example from a prosthetic heart valve.
DECREASED EXCRETION:
low aldosterone - adisons
spironolactone
Acute oliguric renal failure and end stage chronic renal failure
NSIADS and ace inihibitors reduce renin levels and therefore aldosterone.
artifactual: delayed separation - if they say the porters are on strike
also haemolysis is artifactual.
How does addisons present?
acutely abdominal pain, hypotensive shock
fatigue weakness nausea vomiting low grade fever. CONFUSION
Diabetes insipidus
lack of ADH. causes hypernatraemia due to loss of primarily water.
3 causes of euvolemic hyponatraemia
SIADH
hypothyroidism
adrenal insufficiency
what is the difference between cushings disease and cushings syndrome
disease is do to a pituitary tumour
syndrome is everything
how do you diagnose a cushings disease
high dose dexamethasone supression test.
What things precipitate a phaeo to secrete large amounts of adrenaline/noradrenaline
alcohol, sex
What do you find in the urine of CAH?
pregnanetriol.
What is CAH?
absence of cortisol production often noted at birth due to virilisation due to increased androgen production .
80% also have lack of aldosterone
c-anca
wegeners
goodpastures HLA association?
HLA DR2/15
what are the causes of low uptake hyperthyroidism? how do you treat them?
post partum and de quervains
symptom control such as beta blockers.
What type of thyroid tumour produces calcitonin
medullary. part of MEN2 due to its parafollicular cell origin
What does a fat persons cortisol look like?
random will be high but will supress with just low dose
which thyroid tumour produces thyroglobulin
follicular
what is the most common thyroid tumour and how do they present?
paillary
thyroid nodule and lymphadenopthy
hashimotos is likely to give rise to what?
MALToma
What are the causes of hypernatraemia
less comon -
prettty uch water loss from some system unless they are hypervolaemic in which case it may be caused by hypertonic fluids and conns syndrome
causes of cranial and nephrogenic DI?
cranial: head trauma, surgery tumour
nephrogenic:
drugs - lithium
inherited
renal failure
What causes beri beri
b1 deficiency
how do you diagnose DI?
8hr deprivation test
then give desmopressin.
How to you calculate the anion gap
(Na+K)-(Cl+HCO3)
What is a normal anion gap
14-18
What are the causes of an elevated anion gap?
KULT
Ketones
Urea
Lactate
Toxins
how do you calculate the osmolar gap?
Measured minus calculated
should be less than 10.
Which measure is affected first in the assesment of synthetic liver function?
prothrombin time measures the now.
Albumin measures the recent weeks.
What does the AST:ALT ration tell you?
differentiates alcoholic liver disease and viral hepatitis.
alcohol2: 1
viral1: 1
What is the use of GGT
allows you to assess the source of the ALP.
however can be raised in chronic alcohol use.
what does USS of the bile ducts show?
dilated = panc ca, obstructive jaundice.
Undilated = PBC PSC, drugs, preggerz
what drugs can cause cholestasis
augmentin - last 2-3 weeks.
what is the cutoff more micro vs macroadenoma of the pituiatary
10mm
At what level of prolactin is it a prolactinoma
6000
What is acid phosphatase used for?
measuring spread of prostate Ca
What enzyme rises after chemo
LDH
What cardiac markers return to normal very quickly and can be used to assess a second infarction?
myoglobin and CK-MB fall within 48 hours
CK falls in 3 and the others (LDH and trop) take a week
What is osteoporosis circumscripta
pagets lytic skull lesions
What is the mnemonic for organophophate poisining
SLUDGE
Salivation Lacrimation Urination Defecation GI upset Emesis
What are the contraindications to pituitary testting?
IHD and epilepsy
it also wont work if they have untreated hypothyroidism.
What level indicates an adequate response to stress in pituitary testing?
glucos less than 2.2
What do you give if the glucose goes too low
dextrose 20% 50ml through large bore cannulae
What tests can you perform to confirm acromegaly?
glucose tolerance test. and you should suppress growth hormone.
IGF-1 test
What is the treatment for acromegaly
octreotide
what is the treatment for urea cycle disorders?
reduce the amount of ammonina produced by reducing protein intake and giveing sodium benzoate/phenylacetate
which two inborn errors give a high ammonia
urea cycle and organic acidurea
which two inborn erros give you neutropenia
glycogen storage and galactosaemia
what type of bilirubin is always pathalogical?
conjugated
What do you see with APECED
candidiasis,
hypoparathyroidism
addisons
AIRE gene
coirvosiers law
painless palpable gall bladder with jaundice is unlikely to due to gall stone
What is the most comon cause of acute hepatitis
hep A
What are the abnormalities seen in paracetamol overdose?
metabolic acidosis with resp compensation
usualy massice ALT/AST mainly ALT.
high INR and low ph are best indicators of need for transplant
Where are the portosystemic anastomoses
gut
butt
caput
also spleno renal
What does MELAS stand for
mitochondrial encephalopathy, lactic acidosis and stroke like episodes.
which vitamin deficiencies cause dermatitis
b3 and b6
niacin - Dementia, diarrhoe, dermatitis
b6 - pyridoxine, dermatitis,anaemia
lateral reectus palsy
b1 thiamine