Chemical Pathology Flashcards by Joshua Lucas

what is the enzyme missing in lesch nyhan

HGPRT

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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.

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what is high CRP a risk factor for

cardio problems

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what can be broken down to make amino acids

albumin

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high fluid intake as a baby can be a risk factor for what

NEC

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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.

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how do you calculate the osmolarity

2(sodium + potassium) + urea + glucose

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normal osmolarity? what does it help diagnose

serum = 275-295 it is used to diagnose SIADH

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At what point should you treat the hyponatraemia rather than the underlying cause?

when drops below 125.

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What hapens when sodium falls?

N+v - 136
confusion - 131
seizures - pulmonary odema (non cardio) - 125
coma - 117

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What is TURP syndrome

water is absorbed through damaged prostate and causes hypoonatraemia

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How do you differentiate true hyponatraemia from other causes?

osmolality.

HIGH - glucose/mantiol or infusion
NORMAL - spurious, drip arm sample, paraproteinaemia/hyperlipidaemia

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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

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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

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4 causes of SIADH

brain insult
lung pathology
malignancy
drugs - SSRI, carbamazepine, opiates.

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What happens with rapid correction of HYPERnatraemia

cerebral odema
occurs in ITU patients

sx include:
thirst confusion, ataxia,

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What happens with rapid correction of HYPERnatraemia >148mmol/l

cerebral odema
occurs in ITU patients

sx include:
thirst confusion, ataxia, seizures, coma.

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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

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What is the normal range of potassium

3.5-5.5

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What causes tall tented t waves

hyperkalaemia

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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.

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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

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How do you diagnose conns

primary hyperaldosteronism

renin aldosterone ratio.

Renin should be low

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When you are acidotic you are____kalaemic

HYPER

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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