Nephro USMLE**

Question 1

A patient is admitted to the ICU because of severe metabolic acidosis. The serum bicarb is low at 14. The patient is disoriented and cannot offer an adequate hisotry. No records are available. What is the most likely diagnosis when fever, hypotension, tachycardia and an elevated white cell count.

Answer 1

Sepsis. The first step in the evaluation of any metabolic acidosis is the evalution of the anion ga. An anion gap (Na+ minus Cl- and HCO3-) that is >12 is consistent with MUDPILES. Methanol, uremia, DKA, lactic acidosis, elythene glycol, salicylate OD.

Question 2

A patient is admitted to the ICU because of severe metabolic acidosis. The serum bicarb is low at 14. The patient is disoriented and cannot offer an adequate hisotry. No records are available. What is the most likely diagnosis when hyperglycemia and hyperkalemia

Answer 2

HHS or DKA. Gives hyperglycemia and hyperkalemia, although total body level of potassium is depleted.

Question 3

A patient is admitted to the ICU because of severe metabolic acidosis. The serum bicarb is low at 14. The patient is disoriented and cannot offer an adequate hisotry. No records are available. What is the most likely diagnosis when oxalate crystals in the urine and a low serum calcium.

Answer 3

Ethylene Glycol. OD results in oxalate crystals in the urine. The formation of calcium oxalate crystals lowers the calcium level. Look for the term “enveloped shaped” crystals.

Question 4

A patient is admitted to the ICU because of severe metabolic acidosis. The serum bicarb is low at 14. The patient is disoriented and cannot offer an adequate hisotry. No records are available. What is the most likely diagnosis when elevated creatinine.

Answer 4

Renal Failure causes metabolic acidosis because of the kidneys inability to excrete acid.

Question 5

A patient is admitted to the ICU because of severe metabolic acidosis. The serum bicarb is low at 14. The patient is disoriented and cannot offer an adequate hisotry. No records are available. What is the most likely diagnosis when normal anion gap, elevated chloride and hypokalemia.

Answer 5

N anion gap implies either Renal Tubular acidosis or diarrhea. In RTA, the urine anion gap is positive. WIth diarrhea, the urine anion gap is strongly negative. The lower the urine anion gap number, the greater the kidneys ability to excrete acid.

Question 6

A man is admitted to the hospital with renal failure developing over a few days. His creatinine has risen from 0.8mg/dL to 2.5 mg/dL. His BUN has risen even more, giong form 14 - 54. His serum bicarb is slightly low. THe urine sodium is low and the urine osmolality is high. WHat is the most likely diagnosis when his BP is 92/56 and pulse is 124?

Answer 6

Prerenal azotemia from any cause leads to an elevation of the BUN and Cr, with the BUN rising more than the creatinine in a ratio greater than 15:1. The tachycardia and hypotension in the first case suggest hypovolemia or any other form of shock. FeNa <1% also indicates a prerenal etiology.

Question 7

A man is admitted to the hospital with renal failure developing over a few days. His creatinine has risen from 0.8mg/dL to 2.5 mg/dL. His BUN has risen even more, giong form 14 - 54. His serum bicarb is slightly low. The urine sodium is low and the urine osmolality is high. WHat is the most likely diagnosis when serum albumin is 2.2 and the prothrombin time is elevated. There is splenomegaly.

Answer 7

Low oncotic pressure for any reason results in prerenal azotemia because of decreased renal perfusion. In addition, liver disease such as cirrhosis can lead to “hepatorenal” syndrome, which is renal failure entirely on the basis of liver failure.

Question 8

A man is admitted to the hospital with renal failure developing over a few days. His creatinine has risen from 0.8mg/dL to 2.5 mg/dL. His BUN has risen even more, giong form 14 - 54. His serum bicarb is slightly low. THe urine sodium is low and the urine osmolality is high. WHat is the most likely diagnosis when he has an EF of 24% with edema. A diuretic was recently started.

Answer 8

CHF from any cause leads to prerenal azotemia. It can become suddenly worse with the volume depletion from a diuretic. Prerenal azotemia leads to a low urine sodium and high urine osmolality.

Question 9

A man is admitted to the hospital with renal failure developing over a few days. His creatinine has risen from 0.8mg/dL to 2.5 mg/dL. His BUN has risen even more, giong form 14 - 54. His serum bicarb is slightly low. THe urine sodium is low and the urine osmolality is high. WHat is the most likely diagnosis when a bruit is present at the flanks and he has just started an ACE inhibitor

Answer 9

RAS is associated with decreased renal perfusion. Ace inhibitors can precipitate acute renal failure. THink about fibromuscular dysplasia in a young woman.

Question 10

You are called to evaluate a patient because of worsening renal function over the last few days. The creatinine is 2.5mg/dl and the BUN is 28u. The urine sodium is 45 meg/L and urine osmolality is 290 mosm/L. His serum bicarb is low. What is the most likely diagnosis when the patient has been on gentamicin for the last 8 days?

Answer 10

Aminoglycoside induced renal insufficiency generally occurs after 5- 10d of exposure to the medication. As with all forms of acute tubular necrosis, the BUN and creatinine will rise in about a 10:1 ratio. The urine sodium will be high (>40) and the urine osmolality will be low )<350) because of the inability of the damaged kidney tubules to concentrate urine. Amphotericin and any other renal toxic medication will result in the same numbers.

Question 11

You are called to evaluate a patient because of worsening renal function over the last few days. The creatinine is 2.5mg/dl and the BUN is 28u. The urine sodium is 45 meg/L and urine osmolality is 290 mosm/L. His serum bicarb is low. What is the most likely diagnosis when he was on piperacillin for a few days but stopped yesterday. He has a fever and rash and there are eosinophils in his urine.

Answer 11

Allergic interstitial nephritis presents with fever, rash and eosinophils in the urine. The presence of eosinophils in the urine is more frequently found than in the blood.

Question 12

You are called to evaluate a patient because of worsening renal function over the last few days. The creatinine is 2.5mg/dl and the BUN is 28u. The urine sodium is 45 meg/L and urine osmolality is 290 mosm/L. His serum bicarb is low. What is the most likely diagnosis when chemotherapy for lymphoma was started two days ago.

Answer 12

Hyperuricemia from tumour lysis synrome will lead to acute renal failure.

Question 13

You are called to evaluate a patient because of worsening renal function over the last few days. The creatinine is 2.5mg/dl and the BUN is 28u. The urine sodium is 45 meg/L and urine osmolality is 290 mosm/L. His serum bicarb is low. What is the most likely diagnosis when there is an empty bottle of anti freeze at his bedside

Answer 13

Antifreeze contains ethylene glycol, which leads to acute renal failure from oxalic acid accumulation in the kidney tubule. Look for “enveloped shaped oxlate crystals” in the urine. Formic acid accumulates with methanol ingestin causing blindness.

Question 14

A man comes to the emergency department after sustaining a prolonged seizure. He has dark urine which is strongly positive on the dipstick for blood but in which no red cells are seen on microscopic examination. His serum bicarbonate level is low. What is the most likely diagnosis? What is the most specific diagnostic test?

Answer 14

Rhabdomyolysis presents after a crush injury or severe exertion of any kind with dark urine in the absence of visible red cells. This is indicative of urine myoglobin. Rhabdomyolysis leads to metabolic acidosis, hyperkalemia and eventually renal failure. Urine myoglobin is the most specific diagnostic test for rhabdomyolysis. The potassium level and EKG aer pobably the most urgent diagnostic steps because they determine who is most likely to die. The CPK level will be significantly elevated. Administration of IVF and alkalinization of the urine are important. An elevated CPK is not specific for indicating the cause of renal failure.

Question 15

You are evaluating a patient because of confusion. His sodium is low at 122 meq/L. He has no edema, clear lungs, and no JVD. There is no orthostasis. What is the most likely diagnosis when the patient has lung cancer with mets to the brain. Urine sodium is 90 (high) and urine osmolality is 450 (high).

Answer 15

SIADH is caused by any abnormality of the brain or lungs. This can be a cancer, infarction, or infection. SIADH is associated with an inappropriately high urine sodium and osmolarity. The normal response to a low serum sodium should be a low urine sodium adn low urine osmolarity. SIADH is a case of euvolemic hyponatremia. Free water restriction is the treatment.

Question 16

You are evaluating a patient because of confusion. His sodium is low at 122 meq/L. He has no edema, clear lungs, and no JVD. There is no orthostasis. What is the most likely diagnosis when the patient is bipolar, with frequent urination all day that is less at night. Urine sodium is 10 (low) and urine osmolarity (low) 75.

Answer 16

Psychogenic polydipsia is associated with bipolar disorder. There is a normal urinary response to hyponatremia. The normal response is a low urine sodium and osmolarity. A decrease in symptoms at night is the key to the diagnosis. When he goes to sleep he stops drinking, so he stops urinating.

Question 17

You are evaluating a patient because of confusion. His sodium is low at 122 meq/L. He has no edema, clear lungs, and no JVD. There is no orthostasis. What is the most likely diagnosis when the patietn has diabetes with a glucose of 850 (NL 80 - 110).

Answer 17

Pseudohyponatremia is from an elevated glucose for any reason. For every increase in glucose of 100 aboe normal there is a 1.6 point decrease in the sodium.

Question 18

On routine screening, a patient is found to have a low sodium of 127. He has no symptoms of the hyponatremia, and the neurologic exam is normal. What is the most likely diagnosis when the patient has CHF and peripheral edema.

Answer 18

CHF results in hyponatremia because of a decreased intravascular volume. The same effect occurs in cirrhotic patients. This is an appropriate increase in ADH because of the decreased intrvascular volume.

Question 19

On routine screening, a patient is found to have a low sodium of 127. He has no symptoms of the hyponatremia, and the neurologic exam is normal. What is the most likely diagnosis when he has 7g of protein every 24h and the serum albumin is 2.4 (normal 3.5 - 5.5).

Answer 19

Nephrotic syndrome results in hyponatremia because of a decrease in intravascular volume from low oncotic pressure. Nephrotic syndrome here is the most likely diagnosis because of the low serum albumin level as well as the marked increase in protein in the urine.

Question 20

On routine screening, a patient is found to have a low sodium of 127. He has no symptoms of the hyponatremia, and the neurologic exam is normal. What is the most likely diagnosis when the potassium level is elevated at 6.2meq/L (N 3.5 - 5.2) and there is a mild metabolic acidosis.

Answer 20

Addisons Disease or hypoadrenalism of any cause results in hyponatremia. The loss of aldosterone results in the urinary loss of sodium and the retention of both potassium and hydrogen ions.

Question 21

A patient with severe hypernatremia is admitted to the ICU for confusion. There is polyuria despite the increase in serum sodium. The patient is dehydrated. What is the most likely diagnosis when the urine volume markedly decreases in response to the administration of vasopressin

Answer 21

Central diabetes insipidus is an insufficiency of antidiuretic hormone (ADH) due to damage to either the hypothalamus or posterior pituitary. There is a marked response in urine volume to the administration of vasopressin.

Question 22

A patient with severe hypernatremia is admitted to the ICU for confusion. There is polyuria despite the increase in serum sodium. The patient is dehydrated. What is the most likely diagnosis when there is no response to the administration of vasopressin. The urine volume remains high and the urine osmolality remains low.

Answer 22

With nephrogenic diabetes insipidus there is no response to the administration of ADH. NDI is often from hypokalemia or hypercalcemia. There may also be a history of lithium administration.

Question 23

A patient with severe hypernatremia is admitted to the ICU for confusion. There is polyuria despite the increase in serum sodium. The patient is dehydrated. What is the most likely diagnosis when the patient has diabetes and the glucose level is markedly elecated, but the serum bicarb is normal.

Answer 23

Nonketotic hyperosmolar coma results in severe hypernatremia when there is a marked osmotic diuresis from hyperglycemia.

Question 24

A patient is seen because of muscular weakness. There is also an elevated serum bicarb of 30. The potassium level is decreased at 2.9. What is the most likely diagnosis when the vomiting is severe.

Answer 24

Vomiting causing hypokalemia. This is because the metabolic alkalosis from vomiting causes a transcellular shift of potassium intracellularly. This is also because the loss of chloride from the stomach leads to an increase in bicarbonate reabsorption from the kidney. This state is hypochloremic hypokalemic metabolic alkalosis.

Question 25

A patient is seen because of muscular weakness. There is also an elevated serum bicarb of 30. The potassium level is decreased at 2.9. What is the most likely diagnosis when the patient is on a loop diuretic because of CHF.

Answer 25

Diuretics cause hypokalemia because the volume depletion leads to increased aldosterone secretion. All volume contractions lead to metabolic alkalosis by this mechanism. All cases of hypokalemia result in muscular weakness.

Question 26

A man has mild proteinuria, found on a routine urinalysis what is the most likely diagnosis when he is a healthy athlete undergoing intensive physical training.

Answer 26

Mild proteinuria can be found in healthy young athletes undergoing physical training. This is a benign finding and needs no further testing.

Question 27

A man has mild proteinuria, found on a routine urinalysis what is the most likely diagnosis when he is a water. When a split 24h urine is measured, the morning urine has no protein but the afternoon urine shows trace proteinuria.

Answer 27

Orthostatic proteinuria can occur in those who stand up all day long. When the urine is split into a morning and evening protein measurement, there is more in the first eight hours of the day. This is benign.

Question 28

A man has mild proteinuria, found on a routine urinalysis what is the most likely diagnosis when he is generally healthy and the repeat urinalysis shows no protein.

Answer 28

Between 1 - 10% of the population can have transient mild proteinuria. If protein is not found on repeat testing it needs no futher follow up. If persists, a 24h urine measurement or protein/creatinine ratio is performed. Only if the proteinuria is persistent or the ratio is elevated should a renal biopsy be performed.

Question 29

A woman is in your clinic because of edema developing over months. She has a normal echo. Her urinalysis shows 4+ protein and the spot protein/creatinine ration is 7:1. Triglycerides are elevated. What is the most likely diagnosis when there is a history of diabetes and hypertension. The eyes show background retinopathy.

Answer 29

Nephrotic syndrome. combination of edema, a 24h urine protein greater than 3.5g, and hyperlipidemia. A spot portein/creatinine ratio greater than 3.5 is the saem as a 24h urine protein. Diabetes and HTN are the most common causes of nephrotic syndrome. The ratio of protein to creatinine is equal of the amount found on a 24h urine.

Question 30

A woman is in your clinic because of edema developing over months. She has a normal echo. Her urinalysis shows 4+ protein and the spot protein/creatinine ration is 7:1. Triglycerides are elevated. What is the most likely diagnosis when she has been an injection drug user of heroin in the past.

Answer 30

Focal Segmental Glomerulonephritis. IVDU and heroin both cause focal segmental glomerulonephritis. HIV is also associated with focal/segmental disease.

Question 31

A woman is in your clinic because of edema developing over months. She has a normal echo. Her urinalysis shows 4+ protein and the spot protein/creatinine ration is 7:1. Triglycerides are elevated. What is the most likely diagnosis when she was recently diagnosed with lymphoma.

Answer 31

Membranous glomerulonephritis. Most common cause of nephrotic syndrome as a primary disease limited to the kidneys is membranous glomerulonephritis. Membranous glomerulonephritis is also associated with cancer such as lymphoma.

Question 32

A man comes to see you because of persistent hematuria. The urinalysis shows red cell casts and 1+ proteinuria. The urine sodium is low. The most likely diagnosis when the patient is asian with a recent viral illness. There are no systemic manifestations.

Answer 32

IgA nephropathy or Bergers Disease, presents as isolated hematuria at the same time as a viral illness. It is more common in Asians and is the most common cause of acute glomerulonephritis.

Question 33

A man comes to see you because of persistent hematuria. The urinalysis shows red cell casts and 1+ proteinuria. The urine sodium is low. The most likely diagnosis when he has had lifelong eye problems and ear problems with deafness.

Answer 33

Alports syndrome presents with glomerulonephritis in association with eye and ear problems such as deafness. All forms of glomerulonephritis give red cell casts and mild proteinuria.

Question 34

A man comes to see you because of persistent hematuria. The urinalysis shows red cell casts and 1+ proteinuria. The urine sodium is low. The most likely diagnosis when he had a pharyngitis a week ago and has periorbital edema.

Answer 34

Post GAS Glomerulonephritis. leads to tea or cola coloured urine which is proteinuria and hematuria. Periorbital edema is characteristic. The blood will show anti streptolysin O antibodies as a sign of streptococcal infection.

Question 35

A man comes to see you because of persistent hematuria. The urinalysis shows red cell casts and 1+ proteinuria. The urine sodium is low. The most likely diagnosis when he had systemic problems such as petechiae, joint pain, abdo pain and GIB. There is neuropathy. No lung involvement.

Answer 35

Polyarteritis Nodosa (PAN) presents as systemic vasculitis with skin, joint, GI, CNS and neurologic problems. PAN spares the lung.

Question 36

A patient is in your office for evaluation of blood in his urine for the last few days what is the most likely diagnosis when he has burning on urination and must urinate frequently?

Answer 36

UTI of any kind, such as cystitis or pyelonephritis can lead to hematuria. Definitive diagnosis rests on the location of hte pain described in the qustion. Urinalysis and urine culture should still be obtained.

Question 37

A patient is in your office for evaluation of blood in his urine for the last few days what is the most likely diagnosis when he also has pain going form his side into his groin. The pain is extremely severe.

Answer 37

Nephrolithiasis or kidney stones present with severe flank pain radiating to the groin, also known as renal colic.

Question 38

A patient is in your office for evaluation of blood in his urine for the last few days what is the most likely diagnosis when red cell casts and protein are found in his urine as well. Urine sodium is low.

Answer 38

Glomerulonephritis of any kind can present with hematuria. When red cell casts, red cells and mild proteinuria are present the most likely diagnosis is glomerulonephritis. The urine sodium is low because of vasoconstriction of the afferent arteriole. Which is present in all forms of glomerulonephritis.

Question 39

A patient is in your office for evaluation of blood in his urine for the last few days what is the most likely diagnosis when he has recently undergone chemotherapy.

Answer 39

Cyclophosphamide leads to hemorrhagic cystitis.

Question 40

A patient comes in with hematuria, joint pains, and pruritic skin lesions. Urinalysis reveals red cells, red cell casts, and mild proteinuria. The spot protein/creatinine ratio is 1.2 What is the most likely diagnosis when a history of hep C and IgM present in the blood?

Answer 40

Cryoglobulinemia is most often associated with chronic hepatitis C. Cryoglobulinemia leads to renal dysfunction, skin lesions, and joint pains. Neuropathy is common. Both cryoglobulinemia and cold agglutinin disease are from IgM anitbodies in the blood. Cold agglutinin disease, however, leads to hemolysis, not renal dysfunction, and is associated with mycoplasma.

Question 41

A patient is in your office for evaluation of blood in his urine for the last few days what is the most likely diagnosis when a child with abdo pain.

Answer 41

Henoch Schonlein purpura is the most likely diagnosis when the patient is an adolescent or child presenting with GI sx in combination with renal, joint, and skin findings. Palpable purpura of the lower extremities is the key. The most accurate test is a skin biopsy with IgA deposited in the skin, but routine biopsy is not necessary.

Question 42

A 27 yo female comes in because of hematuria and flank pain as well as LLQ abo pain with diverticuli found on colonoscopy. Auscultation shows a mid systolic click. There are cysts found on the ovary and liver as well. What is the most likley diagnosis, what is the most likley cause of death.

Answer 42

PCKD presents with hematuria and can present with kidney stones that occur with increased frequency. In addition to kidney disease, there are also cysts of the liver and ovary with diverticulosis, mitral valve prolapse and aneurysmal diseae in the circle of willis.
The most common cause of death from PCKD is reanl failure. Renal failure occurs from chronic and repeated infections such as pyelo. in addition, there are recurrent kidney stones secondary to the significant anatomic abnormalities. Aneurysm rupture is NOT the most common cause of death from PCKD.

Question 43

A patient comes in with the sudden onset of flank pain and hematuria. What is the most likley diagnosis when there is a history of sickle cell disease. The patient has taken extra doses of multiple pain meds, including NSAIDs. There is some necrotic material in the urine.

Answer 43

Papillary necrosis occurs in patients who have underlying kidney disease such as sickle cell disease or chronic pyelonephritis. The presentation is similar to nephrolithiasis in that there is sudden flank pain and hematuria. However, it often occurs from the use of extra NSAID meds and is associated with nerotic material in the urine. The most accurate test is a CT scan. There is no specific therapy.

Question 44

A patient comes in with the sudden onset of flank pain and hematuria. What is the most likley diagnosis when the pain radiates to the groin in an otherwise healthy person.

Answer 44

Nephrolithiasis presents with sudden flank pain radiating to the groin. The most accurate test is a spiral CT scan. Kidney stones do not need contrast to be visible. XR of the abdo have poor sensitivity. THe IVP is alwasy a wrong choice; it is slow and is associated with the potential for renal insufficiency and allergy from contrast.

Question 45

A man comes to the office and is found to have casts in his urine. What diagnosis is suggested with white cell casts.

Answer 45

Pyelonephritis. They are specific for the disease if present. Generally casts add little to help in diagnosis which is usually obvious from the fever, dysuria, and flank pain and tenderness. (white cell casts)

Question 46

A man comes to the office and is found to have casts in his urine. What diagnosis is suggested with red cell casts?

Answer 46

Glomerulonephritis. (red cell casts)

Question 47

A man comes to the office and is found to have casts in his urine. What diagnosis is suggested with eosinophils?

Answer 47

Allergic Intersitial Nephritis. (eosinophil casts)

Question 48

A man comes to the office and is found to have casts in his urine. What diagnosis is suggested with hyaline casts?

Answer 48

Prerenal azotemia (dehydration). (hyaline casts). They are an accumulation of normal protein which sludges because of decreased renal flow.

Question 49

A man comes to the office and is found to have casts in his urine. What diagnosis is suggested with muddy brown or granular casts?

Answer 49

Acute Tubular Necrosis. The “granules” are sloughed off, necrotic epithelial cells from the kidney tubules.