1. Milk/Soy protein enterocolitis: 
- Presents at age 2-8 weeks
- Often personal or family history of atopy (allergies, asthma, eczema)
- Pathogenesis: non-IgE mediated immune response to dairy and/or soy proteins => colorectal inflammation
- Sx: regurgitation of food/vomiting, bloody stools, eczema
- Treatment: if breastfeeding, mom has to also eliminate milk/soy from diet, if formula-fed, must move to hydrolyzed formula
- Visible bleeding will usually reduce by 3 days, with complete resolution in 2 weeks.
- Usually resolves spontaneously by 1 year of age.
2. DDx GI bleed in infants: 
- Milk/soy protein enterocolitis: vomiting, good appetite, no pain
- Bacterial colitis (fever, decreased appetite, irritability) - rare in breastfed infants due to lack of intake of contaminated food; C.diff is rare in infants due to lack of intestinal receptor to C.diff toxin until approx age 2 years
- Intussusception: intermittent, crampy pain
- Malro + volvulus: ill appearing, bilious vomiting, pain, poor appetite
- Meckel's: rarely presents in neonates
3. Head ultrasound requires open fontanelle - most useful in patients under 6 mos of age.
4. Drugs that cause hyperkalemia: 
- Dig: from inhibition of Na/K ATPase
- K sparing diuretics: ie spironolactone (anti-aldosterone) and triamterine/amiloride (ENaC inhibitor)
- Nonselective B-blockers: inhibit B-mediated cellular uptake of K
- ACE-I/ARB: anti-aldosterone effects
- NSAIDs: anti-aldosterone effects (from impaired local prostaglandin synthesis - prostaglandins cause renin release). Hyperkalemia may be amplified in patients with renal dysfunction (like... from NSAIDs...)
- In this 1985 paper where 50 patients were given indomethacin, 75% had <1mEq increase, 25% had >1mEq incresae
5. Pesudotumor: 
- Diagnosis: no focal deficits (other than a 6th nerve palsy), no evidence of other causes of hydrocephalus, normal CSF except for elevated OP
- Can be caused by tetracycline, isotretinoin.
- Treat with diamox, +/- lasix -- diamox inhibits choroid plexus carb anhyd, decreasing CSF production
- Encourage weight loss
- May need optic nerve sheatlh decompression or LP shunting if unresponsive to medical therapy
- May use steroids and repeated LPs to bridge to definitive treatment.
6. Post cholecystectomy syndrome:
- Persistent or recurrent pain months/years after chole (often same pain as before surgery)
- May be due to biliary (retained stone, sludging) or extrabiliary (PUD, pancreatitis) causes
- Workup with ERCP, EUS, or MR abdomen.    
7. Types of selection bias: 
- Sampling/Ascertainment: nonrandom selection
- Nonresponse rate: high % non-response*
- Attrition: high % loss to follow up*
- Berkson: study only contains inpatients
- Prevalence/Neyman: long lag time between exposure and disease - miss patients who died early or recovered
*: the missing data may represent a distinct group from retained subjects
8. Types of observational bias: 
- Recall: subjects reacall negative outcomes more than positiv
- Observer: observations influenced by bias
- Reporting: subjects lie about incidence of event for various reasons
9. AIN:
- B-lactams, PPIs
- Occurs 7-10 days after drug exposure; may be associated with rash, eosinophilia, pyuria.
10. RBC artifacts 
- Howell Jolly - asplenia
- Heinz - G6PD/thalassmia (denatured Hb) -> bite cells after splenic phagocytes remove them.