Interpreting Mixing studies – Hematology HigYield

via Interpreting Mixing Studies – Hematology Highyield Concept I

Interpreting Mixing Studies – Hematology Highyield Concept I


Archer USMLE Step 3 Blog

Approaching Prolonged PTT and understanding Mixing Studies : 


Question :  On a mixing study, the PTT corrects initially but gets prolonged again after incubation for 2 hours. What is this condition?

This description of mixing studies is consistent with presence of a temperature- and time-dependent anti-VIII inhibitor. It just means that the inhibitor is a warm reacting IgG antibody that requires one or two hour’s incubation at 37°C to be detected. If the PTT corrects initially but prolongs again after incubation (meaning if thePTT is at least 15% longer than the normal reagent plasma’s incubated PTT ) –> anti-VIII should be suspected. This can be confirmed by obtaining a Factor VIII level which will be low in case of presence of inhibitor. Further coinfirmation of Factor VIII inhibitor can be obtained by Bethesda Titer. In such cases, you should also carefully review patient’s prior bleeding history –…

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Question of the Week #490

490. An 18-year-old male presents to the Emergency Department for evaluation of chest pressure for an hour. The pain is radiating to his jaw. On examination, he is diaphoretic, and he complains of nausea. Past medical history is unremarkable. Urine reveals positive benzolegonine. Below is his ECG. What is the most likely cause of the patient’s symptoms?


A. Early repolarization

B. Ischemia

C. Cocaine induced myocardial infarction

D. Atrial fibrillation

E. Wolf-Parkinson-White Syndrome

Question of the Week #489

A 35 Year old woman presents for evaluation of recurrent headaches for the past few months.  Lately, she has been waking up with a headache almost daily though it tends to improve in the latter half of the day. She is frustrated as she can not even get some sleep during the attack since lying down makes her feel worse . She has associated nausea. She has transient attacks of light flashes  that resolve spontaneously. Her menstrual history is unremarkable. On physical examination, she has no neurological deficits. Funduscopic examination shown below: QBANK INSTA AD

Which of the following information, if elicited in the patient history, would increase the clinical suspicion of the diagnosis?

A)     Constipation

B)     Family history

C)      Recent weight gain

D)      Galactorrhea

E)   Urinary Incontinence

Question of the week # 488

A 31 Year old woman diagnosed with suspected diagnosis of Idiopathic intracranial hypertension underwent a lumbar puncture for diagnostic purposes. An MRI of the brain that was obtained prior to lumbar puncture did not reveal any structural abnormalities or mass effect. Laboratory investigations including coagulation parameters were normal. About 12 hours after the procedure, the patient complains of moderate to severe headache. Headache is mainly in the occipital region which increases while sitting up and improves on lying flat. She has two episodes of vomiting in the last one hour. She also complains of dizziness and ringing sensation in her ears.  Physical examination does not reveal any papilledema or focal neurological deficits.

Most appropriate next step in managing this patient?

A) Blood cultures

B) MRI of the Lumbar Spine

C) Non-Contrast CT scan of brain

D) Observation

E) Acetazolamide

USMLE Step 3 Question #487

487) 57-year-old male with a history of mild COPD has been using albuterol as needed to manage his COPD without any other maintenance medications. Recently he has been experiencing a greater degree of shortness of breath, wheezing and a productive cough. Pulmonary function tests demonstrate a FEV1 that is 60% of predicted. What is the next best step for management of his COPD?

A. Add budesonide to treatment regimen

B. Add rofilumast to treatment regimen

C. Add tiotropium to treatment regimen

D. Add tiotropium plus fluticasone to treatment regimen

E. Add carbocystine to treatment regimen


USMLE STep 3 Question #486

A 56-year-old male with Type II diabetes presents to you today for a follow-up visit. Three months prior his A1c was 8.9% and he was started on metformin. Today his A1c is 7.4%. He is significantly overweight with a BMI of 33. You would like to initiate another medication for glucose control, specifically one that does not carry a risk of weight gain. Which of the following drugs is weight neutral?

  • A.  Glimepride
  • B. Rosiglitazone
  • C.  Pioglitazone
  • D. Sitagliptin
  • E. Glyburide
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