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Endocrine (USMLE) high yield Cases

Case: Primary psychogenic polydipsia

Case: Pheochromocytoma

Case: DKA (Diabetic ketoacidosis)

Case: Familial hypocalciuric hypercalcemia

Warfarin and INR Testing USMLE high yield by Dr.Mirza Adnan

The Risk of Bleeding increases with an increase in the INR

Correction of excess anticoagulation is dependent upon the INR value and the presence of clinically significant bleeding

INR < 5, no significant bleeding   --> omit next warfarin dose
INR 5-9, no significant bleeding   --> stop warfarin temporarily
INR > 9  --> stop warfarin, give oral vitamin K


Internal Medicine

USMLE Based Questions

American Diabetes Association (ADA) guidelines for Diabetes mellitus

According to the American Diabetes Association (ADA) guidelines , Diabetes Mellitus (DM) screening should start at age 45 in patients with no DM risk factors. However, patients with risk factors require screening at an earlier age.

The risk factor for developing future DM include excess body weight, family history of type 2 diabetes, and hypertension.

ADA guidelines recommend one of the following DM screening tests.

Plasma HbA1c is a screening modality for diabetes mellitus. Fasting plasma glucose, oral glucose tolerance test, and hyperglycemia in the presence of symptoms can also be used. However the results should be confirmed by repeat testing in the absence of unequivocal hyperglycemia.

Retinoblastoma (intra-ocular tumor)

Retinoblastoma is the most common intra-ocular tumor of childhood. The underlying pathology involves inactivation of the Rb suppressor gene, which may be familial or sporadic.
It is highly malignant tumor, and failure to diagnose and treat the disease early may lead to death from liver and brain metastases. The other manifestations of the disease may include strabismus, decreased vision, ocular inflammation, eye pain, glaucoma, and orbital cellulitis. The diagnosis is highly suspected with Ultrasound or CT scan findings of a mass with calcifications.

Tumor suppressor gene : Rb
Associated tumor : Retinoblastoma , Osteosarcoma
Gene product : Inhibits E2F; blocks G1 -> S phase.

Diagnostic findings : 

Circular grouping of dark tumor cells surrounding pale neurofibrils
Homer-Wright rosettes (neuroblastoma, medulloblastoma, retinoblastoma)

Common Causes of Anion gap metabolic acidosis

Common Causes of Anion gap metabolic acidosis:

1.Lactic acidosis: Hypoxia, poor tissue perfusion, mitochondrial dysfunction

2. Ketoacidosis: Type I diabetes, starvation or alcoholism

3. Methanol ingestion : Formic acid accumulation

4. Ethylene glycol ingestion : Glycolic and oxalic acid accumulation

5. Salicylate poisoning: Causes concomitant respiratory alkalosis

6. Uremia (ESRD): Failure to excrete H+ as NH4+

Indications for Dialysis


Remember : 


A Acid base disorders : Acidemia

E Electrolyte disturbance : Hyperkalemia

I Intoxication i.e methanol, ethylene glycol, lithium , salicylates

O Overload of Volume

U Uremia : Pericarditis , encephalopathy

Retroperitoneal hematoma following femoral arterial catheterization

Cardiac catheterization is typically done by cannulating the femoral artery to access the cardiac vessels. A common complication is hematoma formation in the soft tissue of the upper thigh. If the initial arterial puncture was done above the inguinal ligament, this hematoma can extend directly into the retroperitoneal space and cause significant bleeding, with hypotension and tachycardia.
Patient can also develop ipsilateral flank pain/back pain and neurologic deficits on the ipsilateral side.

The next step in management is to obtain a CT scan of the abdomen and pelvis without contrast to confirm the diagnosis. Treatment is mainly supportive (e.g, blood transfusion, intravenous fluids, and bed rest), with intensive monitoring. If the bleeding continues or the patient is hemodynamically unstable, the patient might need systemic reversal of anticoagulation. Patients who develop neurologic deficits in the ipsilateral extremity require urgent decompression of the hematoma.

Retroperitoneal hemorrhage from an extension of a local vascular hematoma is a common iatrogenic complication of cardiac catheterization. Diagnosis can be confirmed with abdominal CT scan, and treatment is largely supportive.

Legg-Calve-Pethes disease

Legg-Calve-Pethes disease is characterized by osteonecrosis of the femoral head. It typically present in boys age 4-10 years with insidious-onset hip or knee pain and an antalfic gait.

Osler Weber Rendu Syndrome

Osler Weber Rendu Syndrome :

Patients with hereditary telengiectasia can develop pulmonary AVMs associated with hemoptysis and right to left shunt physiology. Also with recurrent nose bleeds and oral lesions.