1. Susceptibility bias: when treatment regimen selected depends on the severity of the patient's illness (i.e. crossover effect). Type of selection bias.
2. Conjunctivitis: 

- Bacterial: manage with erythromycin ointment, polymyxin-trimethroprim drops, azithro drops or fluoroquinolone drops (preferred in contact lens wearers) 

- Viral (usually adenovirus in summer/fall): warm/cold compresses, antihistamine or decongestant drops. Steroid drops are contraindicated. 

- Allergic (sx similar to viral but shorter duration): OTC antihistamine/decongestant drops, mast cell stabilizer/antihistamine drops for frequent episodes. 

- Mast cell stabilizing agents  - olopatadine, azelastine

3. HSV keratitis: 

- painful red eye

- impaired vision

- corneal ulceration 

- corneal opacification 

4. ACTH secreting tumors: 

- Tumors that secrete lots of ACTH and raise levels quickly (malignant tumors like small cell) cause more of the Aldosterone/mineralcorticoid effects - hypertension, hypokalemia, metabolic alkalosis, hyperpigmentation without the classical "cushingoid" effects. Cortisol has high affinity for mineralcorticoid receptors, but is generally converted to cortisone (inactive) by 11-B-hydroxyl dehydrogenase (11-beta-HSD) in kidneys; but when ACTH secretion is rapid and high the enzyme is saturated, leading more cortisol available to activate mineralcorticoid receptors 

- Tumors that secrete ACTH slowly and raise levels slowly (benign tumors like carcinoids) cause more of the cushingoid symptoms - moon facies, buffalo hump, striae 

- Ectopic ACTH causes worse HTN and hypoK than endogenous. Perhaps because it doesn't respond to the natural negative feedback patterns? 

5. Adrenal insufficiency: 

- Most common cause in developing countries is TB (calcifications in bilateral adrenal glands is pretty typical of TB). Adrenal function usually does not return after treatment of TB, and people need to be on lifelong glucocorticoids and mineralcorticoids 

- Most common cause in developed countries is autoimmune - responsible for 80% of patients with primary adrenal cortical insufficiency. You will not see calcifications on CT 

- In HIV+ patients, CMV, atypical mycobacteria, fungi, and TB are common causes of adrenal insufficiency; antifungals (like ketoconazole) can precipitate AI by inhibiting adrenal steroid synthesis 

- AI due to adrenoleukodystrophy - accumulation of very long chain fatty acids in adrenal glands - will show enlarged adrenal glands with no calcifications 

6. Eye infections: 

- Dacryocystitis: lacrimal sac infection, usually infants and adults > 40, sudden onset of pain and redness in medial canthus, usually s.aureus and beta hemolytic strep. Treat with systemic antibiotics 

- Episcleritis: infection of episcleral tissue between conjunctiva and sclera. Conjunctiva - thin layer of stratified squamous epithelium that lines inside of eyelids and covers "whites of eyes" (sclera) 

- Hordoleum: abscess on upper or lower eyelid, usually s.aureus - localized red, tender swelling

- Chalazion - chronic granulomatous inflammation of meibomian gland - hard, painless lid nodule. 

- Orbital cellulits: behind orbital septum (ie. orbital rim to eyelids) - proptosis, ophthalmoplegia, fever. 

7. Veiscoureteral reflux (VUR) is estimated to be present in 30-45% of children with UTI. 

- American academy of peds recommends all kids 2-24 mos with first UTI should undergo renal u/s to eval for anatomic abnormalities that may predispose to VUR

- VCUG should be done in any kids with recurrent UTI, but not after the first. 

8. Steroid mediated adrenal insufficiency: 

- Leads to decreased ACTH and cortisol, but aldosterone levels are generally normal since that's more regulated by renin-angiotensin and K levels

- May be associated with hyponatremia, as cortisol normally suppresses ADH secretion; in the absence of cortisol, an SIADH picture may occur 

9. Diagnosing cause of renal failure 

- <10 mEq/liter is considered low, and consistent with pre-renal 

- Hepatorenal syndrome has prerenal component as splanchnic vasoconstriction robs perfusion pressure 

- Clean dipstick suggests against intrinsic renal pathology 

- Cr does not rise with obstructive uropathy unless both ureters are obstructed 

10. Bipolar with psychotic features vs schizoaffective: 

- In bipolar with psychotic features, the psychotic episodes occur only when the mood symptoms occur. 

- The diagnosis of schizoaffective disorder is only applicable if the patient has psychotic symptoms in the absence of mood symptoms for at least 2 weeks. 

- Vs schizophrenia: in schizophrenia, the mood symptoms are a minor component of the disease and occur rarely. In the above 2 diagnoses, the mood components are a significant component of the disease and occur more often than not.