Metabolics and Immunology

Question 1

Summarise HIV

Answer 1

Pathophysiology: virus that lowers the CD4 count so become immunocompromised.
<200 CD4 = AIDS

RF: unprotected sex, sex work, vertical transmission, IVDU, needle stick injury, transfusion/ tattoos abroad

Presentation:
Initial - flu-like illness then asx for years
Later: Fatigue, diarrhoea, lymphadenopathy, rash
Late: Opporunisitic infections –> TB, kaposis sarcoma, lymphoma, CMV, candida, PCP

Ix: Blds- antibody test. PCR gives viral load.

Mx: 
Anti-virals: tenorovir + emticitabine (HAART)
PreP and PEP for prevention.
Co-trimoxazole for PCP
Yearly cervical smears 
Vaccines (No live)

Question 2

Summarise Malaria

Answer 2

Pathophysiology: Anopheles mosquitoes act as vector to give protozoan parasite P.falciparum (most common); P. ovale; P.vivax. This travels to the liver, entering the RBC and then reproducing in these to then rupture and spread parasite –> Haemolytic anaemia

Presentation:
Incubation: 1-4 weeks (may lie formant for yrs)
Night sweats, fever, malaise, N+V, anaemia signs, hepatosplenomegaly, jaundice
Severe: seizures, LOC, AKI, pulmonary oedema, DIC

Ix: Blood film - 3 samples over 3 consecutive days

Mx:
PO Artemether with lumefantrine (Riamet) if uncomplicated.
IV artesunate if complicated.
Admit if falciparum malaria as can deteriorate quickly.

Question 3

Summarise Hypersensitivity Types

Answer 3

Type I: IgE mediated e.g. asthma, eczema, hayfever, food allergy - if mast cells released = allergic reaction

Type II: Ag-Ab complexes e.g. ABO incompatibility, haemolytic newborn reaction, goodpasteurs

Type III: Ab-AB complexes travel to area –> inflammation e.g. RA, farmers lung

Type IV: Delayed, T helper e.g. gold, posion ivy, mantoux test

Question 4

Summarise Anaphyalxis

Answer 4

Pathophysiology: Severe Type 1 hypersensivity reaction where mast cells rapidly release histamine –> ABC compromised

Presentation: Angioedema, SOB, deranged obs, urticaria, itching, wheeze, abdo pain, stridor, collapse

Ix: Later confirm with tryptase

Mx:
ABCDE (airway, oxygen, salbutamol, IV bolus, lie flat to improve cerebral perfusion)
IM adrenalin
antihistamine e.g. chlorphenamine
IV hydrocortisone
Need observation as biphasic reactions can occur

Later:
Epipen, allergy education,

Question 5

Summarise Hyperkalaemia

Answer 5

Causes:
Drugs (potassium sparing diuretics, ACE-i, ARB, NSAID)
Haemolysis causing artefact on blood test 
AKI
CKD
Tumour lysis syndrome
Addisons 
Rhabdomyolysis

Ix:
ECG - Tall tented T waves, flattened P, broad QRS

Mx:
>6 mmol/L + ECG changes or >6.5 need urgent treatment
Actraid 10 units + Dextrose 50mls of 50%
Calcium gluconate

Other options: Neb salbutamol, IV fluids, sodium bicarbonate in AKI, dialysis

Question 6

Summarise Hypokalaemia

Answer 6

Criteria: <3.5mmol/L

Causes:
Drugs (thiazide diuretics, psych meds, insulin, salbutamol, verapamil, laxatives)
Loss (vomit, burns, diarrhoea)
Hypomagnesia 
Cushings 
Dialysis

Ix: ECG shows Flattened T waves, QT prolongation, U waves, ST depression

Mx: Replace at rate 10mmol/ hr

Question 7

Summarise Hypercalcaemia

Answer 7

Adjusted calcium concentration of > 2.6 mmol/L

Causes:
Primary hyperparathyroidism
Malignancy
Renal Disease
Drugs
Granuloma diseases

Sx: Bone pain, OP, fatigue, confusion, depression, N+V, constipation, abdo pain, renal stones

Mx: Address cause

Question 8

Summarise Hyponatraemia

Answer 8

<130mmol/L, severe <125mmol/L

Causes: Drugs (thiazide Diuretics, SSRIs), HF, renal disease, LF, SIADH, Addisons

Sx: N+V, headache, LOC, seizure, arrest

Ix:
Assess volume status, serum and urine osmolality, urine sodium concentration

Question 9

Summarise Hypernatraemia

Answer 9

> 145 mmol/L, severe >160mmol/L

Causes: Dehydration and fluid loss, acute tubular necrosis, loop diuretics, DI, hypertonic saline

Mx: Correct with hypotonic fluids (0.45% saline, 5% dex, PO water) but avoid >0.5mmol/L/hr to stop osmotic demyelination