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Achalasia
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Scombroid fish poisoning
Scombroid poisoning or scombroid fish poisoning occurs after consuming fish that contain high levels of histamine. This is often seen when eating fish that has not been properly stored or refrigerated. The amino acid histidine in the fish is converted to histamine by bacterial enzymes as the fish decomposes. High levels of histamine, even toxic levels, can be present in decomposing fish even before there is a noticeable smell or taste. The reaction is similar to an allergic reaction and occurs during , immediately after eating or a few hours later. Symptoms include vomiting, diarrhea and hives. Other symptoms include: flushing of the skin, itchiness, palpitations, rash, tingling, stomach pain,…
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Acetaminophen
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Rubella
Rubella, also known as the German measles, is a viral infection characterized by an erythematous maculopapular or morbilliform rash that typically begins on the face and head and generalizes over 24 hours i.e. it spreads downwards towards the trunk and limbs. It is often called the 3 day measles because the rash lasts about 3 days. The rash may be itchy and is accompanied by a low fever and enlargement of lymph nodes in the post-auricular, sub-occipital, and posterior cervical regions (behind the ears, head, and neck). In children, the rash is often the first sign, whereas in adults, the lymphadenopathy and other non-specific symptoms (headache, malaise, cough, conjunctivitis) may…
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Pneumonia
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Cylindroma
Cylindromas are smooth, round benign tumors of eccrine sweat glands that are most often found on the scalp. They often occur in clusters and may be compared to a bunch of grapes. In rare cases, the tumors coalesce and form one large tumor that covers the entire scalp. This is called a “turban tumor.” Hereditary cylindromas are often multiple and are inherited in an autosomal dominant manner. Sample Cases A 45 year old man presents with two small, round, 1 cm masses on his scalp. They have grown larger over the last 6 months. On exam, the masses are solid and move under the skin of the scalp. The overlying…
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Hot Tub Folliculitis
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Renal Formulas
Name Formula Notes Fractional excretion of sodium (FENa) (urine sodium x serum creatinine) / (serum sodium x urine creatinine) <1% suggests pre-renal and other causes. Useful in assessing oliguria or acute kidney injury Fractional excretion of urea (FEUrea) (urine urea x serum creatinine) / (serum urea x urine creatinine) <35% suggests pre-renal and other causes. Useful in assessing hyponatremia Urine Anion Gap sodium + potassium – chloride Useful in assessing a normal anion gap metabolic acidosis. A + UAG suggests renal cause of acidosis Transtubular potassium gradient (TTKG) (urine potassium x serum osmolality) / (serum potassium x urine osmolality) A high TTKG suggests renal potassium loss. Useful in assessing hypokalemia.…
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Biostatistics Formulas
Part 1: The formulas Part 2: Explanation of the formulas Formulas & Tables Disease + Disease – Test + true positive (TP)a False negative (FN)b a+b PPV = a/(a+b) Test – False positive (FP)c True negative (TN)d c+d NPV = d/(c+d) a+c b+d total SN = a/(a+c) SP = d/(b+d) For Diagnostic tests Formula Sensitivity, SN (true-positive rate) = TP/ (TP +FN) which is a/(a+c) Specificity, SP (true-negative rate) = TN/ (TN + FP) which is d/(b+d) Positive predictive value (PPV) = TP / (TP + FP), which is a/(a+b) Negative predictive value (NPV) = TN / (TN + FN), which is d/(c+d) Incidence rate = # of new cases…
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Bias in Research Studies
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Best Physiology Books
While all of the physiology textbooks and review books we list are excellent study sources, you may decide to choose one over another based on your study goals. For board exam preparation, we recommend a quick read that covers the most high yield topics such as BRS physiology accompanied by a question bank such as Usmle World. For students in their first or second year of study, we recommend an introductory book that is comprehensive such as Guyton and Hall’s textbook of medical physiology. Rank Book Rating 1 Physiology by Costanzo 9.5 2 Guyton and Hall Medical Physiology 9 3 BRS Physiology by Costanzo 9 4 Ganong’s Review of Medical…
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How to Study for Step 1 Usmle
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Step 2 CK Resources
First Aid for the USMLE Step 2 CK This is one of the most commonly used review books for step 2 CK. While you shouldn’t use it as your only review book, it does a decent job of covering the basic topics you will need to know. We found it to not be comparable to First Aid for the Usmle Step 1, which is considered a gold standard for preparation, however, it is a decent option that will not break the bank.
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How to Study for Step 1 Usmle
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Alcohol Withdrawal
A 45 year old man comes to the office because he wants to quit drinking alcohol. He reports that he drinks about 12 to 15 beers daily and the occasional cup of wine with dinner. His last drink of alcohol was yesterday, about 24 hours ago. He tells you he feels odd and thinks he has been hearing voices. On exam, his pulse and heart rate are elevated (100 bpm, 160/100 mmHg) and he has a visible tremor, mild diaphoresis and appears agitated. You administer the clinical institute withdrawal assessment scale for alcohol, revised (CIWA-Ar score). His score is 18. A 45 year old man is brought to the emergency…
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Head and neck squamous cell carcinoma (HNSCC)
A middle aged woman with chronic sore throat, worse with swallowing especially solids, and bad breath comes to the clinic. On exam, there is an enlarged firm right tonsil with a 2 cm ulceration. Also, 2 enlarged firm, fixed, nontender lymph nodes in the right side of her neck. What is the most likely diagnosis, the most likely underlying etiology, and the next step in management? She most likely has head & neck squamous cell carcinoma due to HPV and the next steps involve getting a biopsy, HPV status, CT scan and endoscpy. An elderly patient with long history of heavy smoking has chronic sore throat that doesn’t get better…
