A 74-year old man presents in the emergency room with weakness, back pain and decreased urinary output. His calcium is 13.2 mg/dL (Reference interval: 8.5 – 10.5 mg/dL). The serum creatinine is 1.9 mg/dL (reference interval: 0.5-1.2 mg/dL). His hemoglobin is 11 g/dL (reference interval: 12.5-16.5 g/dL). Two days later a renal biopsy is performed (see image). What is the most likely underlying pathogenesis of this disorder? 

A 7 y/o girl presents with hypertension. Her father and paternal grandmother developed hypertension before age 20. The AM laboratory studies are presented when she is receiving no medications. Previously DOC (desoxycorticosterone) was reported as within the reference interval. Abdominal CT is negative for adrenal masses. Based on these data, of the following choices, what is the most likely cause of the patient’s hypertension? 

What is the major site for the regulation of renal potassium excretion?

A 32-year old male develops persistent hematuria. A renal biopsy is performed. Light microscopy shows mild mesangial hypercellularity. The image shows a representative image of immunofluorescence staining for IgA. Which statement is true concerning this condition? 

A 68-year old previously healthy male presents with a several week history of weight loss and malaise. Laboratory studies reveal increased serum creatinine and markedly increased urinary protein (14 grams/24hours). Monoclonal light chains are detected in the urine. A renal biopsy is performed (see H&E image). IF and EM are being performed. What would be the next best procedure to perform on the biopsy section to make the diagnosis? 

Anatomically where do medications in clinical use that treat hyperphosphatemia have their effect to reduce the patient’s phosphate levels in their blood?

Electron microscopy of a glomerulus from the kidney biopsy of a 12 year old female patient with the nephritic syndrome is displayed. Which other clinical finding would most likely be expected in this patient? 

A 75 y/o man with the recent diagnosis of acute decompensated heart failure reports little to no urine output. His bladder is empty on ultrasound. What is the most likely cause of his oliguria? 

An alcoholic man drinks 10 beers per day and does not eat. Note that beer has very little solute (~2 meq/L of Na+; in contrast, Gatorade has 20 meq/L of Na+). He is brought to the ED because his sister (with whom he lives) notes that he is unresponsive except to deep pain. His renal function is normal. Predict his serum sodium concentration (reference interval: 135-145 meq/L) based upon the choices provided.

A 18 year old obese male presents with severe edema. Urinary protein is 8g/24 hr. A renal biopsy is performed. On light microscopy (LM), 20% of the glomeruli have the lesion illustrated in the image. Immunofluorescence (IF) showed some glomerular low intensity IgM staining but electron microscopy (EM) reveals no deposits. What is the best diagnosis?