Clinical Biochemistry Flashcards
What indicates a carcinoid syndrome?
High plasma chromogranin a conc
Which substances have 5HIAA in them?
Walnut chocolate
Tomoatoes aubergines avocado
Plums bananas kiwi and pineapple
Why happens in carcinoid tumours?
Starts in GIT, seretonin is metabolised,
To show symptoms liver has to be dysfunctional e.g due to liver metastasis
How to detect a carcinoid?
Somatostatin receptor scintography
Where is plasma chromagranin A present?
In secretory vesicles
What can be measured of ADH?
Copeptin, a cleavage product
What else is a tumour marker?
Serum calcitonin, from medullary c cells thyroid
ADH and oxytocin are released where?
Inferior hypophysis artery
Circadian rhythm of pituitary hormones is controlled by?
Supraoptic nucleus of hypothalamus
What can cause neural tube defects?
Genes, environment plus folate deficiency, maternal T1DM, and use of certain anticonvulsants
How do you screen for neural tube defects?
Maternal serum alpha fetoprotein
Fetal ultrasound
Alpha fetoprotein is produced by?
Fetal liver and yolk sac
What is alpha fetoprotein in adults a marker of?
Teratocarcinoma
New hepatocytes, liver regeneration, heaptocellular carcinoma
Too low alpha fetoprotein then?
Downs
Too high alpha fetoprotein then?
Spina bifida
Low sodium results in
Cramps decreased reflexes and encephalopathy
High sodium results in?
Weakness increased reflexes tremor encephalopathy
Low potassium results in?
Weakness normal reflexes paresthesis
High potassium results?
In decreased reflexes weakness
Low calcium results in ?
Tetany
Encephalopathy
High calcium results in ?
Weakness increased reflexes encephalopathy
Low mg results in?
Tetany increased reflexes and encephalopathy
High magnesium results in
Flaccid paralysis
Low phosphate results in?
Flaccid paralysis
Hyperventilation can cause?
Hypocaclaemia, because more calcium binds to albumin as there is less hydrogen
Hence respiratory alkalosis
Fabry disease?
Don’t have enzymes to break down lipids
Refsum’s disease?
Weakness or numbness of hands and feet, peripheral neuropathy
Whippets, nitrous oxide use?
Degeneration of spinal cord and peripheral neuropathy because it coverts b12 from active to inactive form
What is the role of active b12?
Coenzyme for methionine synthase, to allow generation of methyl groups for synthesis of several products including rna dna and myelin
Neuropathy due to b12 commonly seen in?
Older people with macrocyclic anaemia, antibodies against gastric parietal cells and intrinsic factor
Symptoms of meningisim?
Headache, stiffness, photophobia nauseau and vomiting
If you have inflammation of meninges what will you find?
Blood in CSF, either from SAH or traumatic tap
Will show as oxyhaemogobin or metabolised to bilirubin
How should you label CSF?
- White top universal specimen for micro 10 drops
- White top univ specimen for biochemical 20 drops
- White top for micro to ensure cell count decreasing 10 drops
What else should you check in CSF?
Glucose CSF to serum is 0.6
Protein bilirubin, lactate xanthocromia and oligoclonal bands
Why a 12 hour delay before lumbar puncture?
Conversion from haemoglobin to bilirubin
What will you find in MS?
Positive CSF oligoclonal bands
How are tangles formed?
Hyper phosphorylated tau, which is needed for micro tubules, loses its ability to bind to micro tubules and stimulate their assembly leading to neuronal damage
How are plaques formed?
Ab deposits , ab42
What is combo for Alzheimer’s?
Low Ab42 and elevated tau in CSF
Importance of ApoE?
ApoE4 tend to promote plaque formation
APoE2 inhibits plaque formation
What investigations would you do in dementia?
FBC and ESR- anaemia and vasculitis Calcium- hypo and hyper Folate and b12 Hba1c- diabetes Liver function tests Sodium potsssium creatinine- CKD electrolyte disorder Thyroid function tests- hypo Syphilis and hiv serology Systemic lupus
Drippy nose, what would you check for?
Test for asialotransferrin, b transferrin- high conc
Low in plasma, high in CSF
What can cause altered consciousness?
Alcohols Epilepsy, electrolyte disorders and hepatic encephalopathy Infection Opiates, overdose and oxygen Uraemia Trauma, toxins, tumour, temp Insulin, in born errors of met Poisoning psychogenic Space occupying lesion, stroke, seizure shock
How to check for cerebral hypoxia?
Serum neurone specific enolase NSE
Glycolysis enzyme released following neuronal cell death
Anything above 16 micro gram/l
What can cause cerebral oedema?
Rapid reduction of plasma glucose in treatment hyperosmolar hyperglycaemia with insulin or diabetic ketoacidosis
Hyponatraemia:
Excessive IV administration of hypotonic fluids
Excessive water intake due to ADH- siadh
Ectopic ADH secretion
MDMA
Causes of encephalitis
Viral - PCR
• Person-to-person eg herpes simplex, measles, mumps etc
• Animal eg ticks (tick-borne encephalitis), dog (rabies)
• Other pathogens – eg toxoplasma, amoebae
Auto-immune:
• Post-infectious - acute disseminated encephalomyelitis (ADEM)
• Tumour associated - Hu, Yo, Ri, Ma, Amphiphysin, CRMP5/CV2, Tr
• LGI1 (leucine-rich glioma inactivated 1) or CASPR2 (contactin-associated protein 2) causing ‘limbic encephalitis’.
• N-methyl-D-aspartate (NMD
Glutamic acid decarboxylase anti GAD Is used when?
Stiff person syndrome
Voltage gated ca2 channel antibody used when?
Cerebellar ataxia lambert eaton
Anti ganglioside gm1 used when?
Guillian barre and miller fisher
Copper deposition found in?
Wilsons
Accumulation of mucopolysaccharides
Hurler syndrome
Accumulation of sphingolipids?
Gaucher
Anxiolytics drugs is?
Diazepam
Antipsychotic drugs?
Chlorpromazine, haloperidol, respiridone, clozapine
Mania and bipolar drugs?
Lithium
Antidepressants?
Amitypilline and fluoxetine
Analgesics?
Paracetamol, ibuprofen, codeine phosphate morphine
Anti migraine drugs?
Pizotifen
Antiepileptics?
Carbamazepine, phenobarbitone, phenytoin, sodium valproate
Parisians drugs?
Levodopa
Entacapone selegiline
Ropinirole
Dementia drug?
Donepezil
Anaesthetics?
Lidocaine, propofol
Opioid antagonist?
Naloxone
Neuromuscular blocking drugs?
Suxamthonium
Target therapeutic range is?
10-20 mg/l
What does phenytoin do?
Activates enzymes that inactivate vit d, so less calcium , hence elevated PTH
Consequences of hyperprolactinaemia
Diminished ejaculator volume oligospermia lots of libido or sexual dysfunction galactorrhoea infertility gynaecomastia oligoria amenorrhea atrophic changes in vagina mucosa reduced vagina lubrication
Acne hirsutism
Therapeutic window for lithium?
0.4-1 mmol/l
Toxicity of lithium?
Acute vomiting and diarrhoea dizziness
chronic course tremor hyperflexia nystagmus ataxia altered mental state
Endocrine effects of lithium?
Hypothyroidism
Decreased sensitivity to ADH
Causing polyuria and hypernatraemia
Adjust calcium receptors in PTh glands leading to increased PTH secretion and hypercalcaemia
Lithium monitoring?
Every 3 months
Renal. Function
Thyroid
Serum calcium,
What can induce hypogonadism?
Opiates, reduced gonadotropin secretion
hyperprolactinaemia
Antiepileptic increase SHGB and suppress axis
Decreased conc of pseudocholinesterase can cause?
Unable to breathe and move on their own because suxamethonium and mivacurim mimic action of acetycholine but slowly
Tests for pseudocholinesterase deficiency?
Dibucaine and fluoride - inhibitors
Pseudocholinesterase deficiency happens?
Autosomal recessive in BCHE gene.
I in 3200 to 5000
Persian Jews and Alaska natives
