​Differential diagnosis of anorectal pain: 
-solitary rectal ulcer syndrome 
-rectocele 
-proctalgia fulgax
-levator ani syndrome 
-anal cancer
-rectal cancer
-pruritus ani 
-lymphogranuloma venereum ( proctocolitis, anorectal strictures, fistulas, perianal ulcer) 
-secondary syphilis ( condyloma lata) 
-anorectal herpes simplex
-anal fissure due to trauma, leukemia, tuberculosis, Crohn’s disease, 
-anal skin tag
-rectal prolapse
-intussusception 
-infectious proctitis such as chalmydia, syphilis, gonorrhea, 
-perianal fistula 
-perianal abscess
-Crohn’s disease
-hemorrhoids 

​Differential diagnosis of anogenital pruritus:
-strongyloidiasis
-enterobiasis (pinworm infection) 
-lichen sclerosis 
-diarrhea
-vaginal discharge 
-erythrasma 
-herpes simplex virus 
-tinea 
-candidiasis 
-contact dermatitis 
-seborrheic dermatitis 
-lichen simplex chronicus 
-hemorrhoids 
-psoriasis 
-intertrigo 
-idiopathic 

​Differential diagnosis of annular rash: 
-erythema nodosum 
-granuloma annulare 
-erythema migrans 
-lyme disease
-discoid lupus erythematosus 
-nummular ( discoid) eczema 
-pityriasis rosea 
-erythema multiforme 
-secondary syphilis 
-psoriasis 
-tinea corporis ( body ringworm) 

​Differential diagnosis of increase in amylase: 
-narcotic administration 
-macroamylasemia 
-abdominal surgery 
-pelvic inflammatory disease
-ruptured ectopic pregnancy 
-peritonitis 
-penetrating duodenal ulcer 
-diabetic ketoacidosis 
-parotitis due sarcoidosis 
-mumps 
-intestinal infarction 
-intestinal obstruction 
-acute pancreatitis 
-pancreatic duct obstruction due to pancreatic cancer, choledocholithiasis, cholecystitis) 
-pancreatic pseudocyst 

​Differential diagnosis of secondary amenorrhea: 
-anabolic steroids
-endometrial scarring ( Asherman’s syndrome)
-pregnancy 
-anorexia nervosa
-Turner Syndrome 
-acromegaly 
-congenital adrenal hyperplasia
-androgen secreting tumor
-hypopituitarism 
-Addison’s disease
-Cushing Syndrome 
-premature ovarian failure 
-diabetes mellitus
-hypothyroidism 
-hyperthyroidism 
-hyperprolactinemia 
-hypothalamic amenorrhea due to stress, exercise, weight change 
-polycystic ovary syndrome 
-menopause 
-perimenopause 

​Differential diagnosis of raised alkaline phosphatase : 
-hemochromatosis 
-infiltrative liver disease 
-tuberculosis 
-sarcoidosis 
-amyloidosis 
-lymphoma 
-viral hepatitis 
-alcoholic hepatitis 
-toxic hepatitis 
-perforated viscus 
-bowel infarction 
-third trimester pregnancy 
-hyperparathyroidism 
-osteosarcoma 
-osteomalacia
-Paget’s disease
-bone metastases
-obstructive hepatobiliary disease

​Differential diagnosis of altered mental status in diabetic 
-uremia 
-stroke 
-hypoglycemia 
-sepsis
-lactic acidosis 
-metformin use 
-severe infection 
-hyperglycemic hyperosmolar state 
-diabetic ketoacidosis 

​Differential diagnosis of general causes of altered mental status: 
-heat stroke 
-seizure
-ICU psychosis
-hypothermia 
-“sundowning”

​Differential diagnosis of psychiatric disorders causing altered mental status:
-depression 
-schizophrenia 

​Differential diagnosis of vascular causes of altered mental status: 
-hyper viscosity
-stroke 
-coronary ischemia 
-subarachnoid hemorrhage 
-hypertensive encephalopathy 
-thrombotic thrombocytopenic purpura 
-CNS vasculitis 
-disseminated intravascular coagulation