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Discussion Starter #1
A 65 year-old male presents with a 4-6 month history of intermittent production of red-tinged urine. Physical exam
reveals a well nourished patient with slightly enlarged prostate and no other abnormal findings.

Initial laboratory data reveals:

-hemoglobin 18.7 g/dl (normal: 13.0-18.0 g/dL)
-hematocrit 58% (normal: 37-49%)
-BUN 10 mg/dl = urea of 3.6 mmol/L (normal: 8-25 mg/dL or 2.9-8.9 mmol/L)
-creatinine 0.8 mg/dl = 70 μmol/L (normal: 0.6-1.5 mg/dL or 52-132 μmol/L)
-calcium 12.3 mg/dl = 3.1 mmol/L (normal: 8.5-10.5 mg/dL or 2.1-2.6 mmol/L)
-urinalysis: ++ hematuria, + PMN.

The patient's lab results are most consistent with which of the following?

A. Dehydration
B. Paraneoplastic syndrome
C. Renal hematoma
D. Cystitis secondary to E. coli
E. Renal calculi

??????
 

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I think its

B. Paraneoplastic syndrome
 

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I think its RCC coz RCC causes polycythemia. Inc. prostate size may be due to age related BPH.
 
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Y Not A?

The answer looks like paraneoplastic syndrome due to RCC. But its a hard q. So lets deviate our thinking and rule out the other possibilities.

1. With Hb% almost within normal range, and the Hct elevated, it may be relative polycythemia.
2. Hypercalcemia cannot be explained by RCC. (Atleast I can't explain that)
3. RCC in the usual USMLE format q are explained as frank haematuria. This one which is intermittent could be probably prostatitis/ renal calculi

So why don't we explore the possibilities of the answer to be 'dehydration'. (Can exacerbate renal calculi though I still can't find the reason for hypercalcemia)

----------------
Pardon me for being different
 

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RCC...produces ectopic hormons...like Erythropoiecin (EPO)...responsible for polycythemia...
PTH related peptide...causing hypercalcemia...n renal stone...
regarding hematuria...it occurs only in 50 to 60% pt....though he is having intermittent production of red-tinged urine...
 

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Then probably the haematuria is bcoz of the calculi rather than b coz of RCC. But can anyone please explain me how to diff between relative polycythemia and absoulte polycythemia with these lab values
 

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I guess the dehydration with that high Hct should probably be in prerenal ARF. Since BUN:Cr values does not suggest one, dehydration can be ruled out.
 

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Great discussion going on here! I will post the answer+explanation and new CHALLENGING question sometime today!
Waiting eagerly for the answer even though i positively feel Paraneoplastic syndrome is the right answer, however my feelings have been crushed a number of times by the questions here. :p
 

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Discussion Starter #17
ANSWER+EXPLANATION (From MedicalExams.com)

Ok, ok, ok I've made you guys wait long enough haha.

Here's the answer.

The correct answer is Choice B.

This patient has a combination of polycythemia (erythrocytosis), hematuria, and hypercalcemia. His urea/BUN is in the normal
range and this excludes dehydration as the cause of his elevated hematocrit, and it would not explain his intermittent hematuria.

Renal hematoma generally follows trauma (non-traumatic renal hematoma can occur but it rare), and there is no suggestive history here. Like cystitis and renal calculi this diagnosis does not explain the hypercalcemia or the erythrocytosis.

The combination of laboratory findings is compatible with a diagnosis of paraneoplastic syndrome. Although hypercalcemia can
occur in many tumor syndromes, the presence of hematuria suggests that this patient may have a renal tumor, and renal cell
carcinoma (RCC) would be high up the list of differentials.

RCC originate from renal tubular epithelium and account for 95% of all renal tumors and around 2-4% of all malignancies. Around
30% of RCC patients present with metastatic disease, most often lung followed by soft tissue, bone, liver, skin and central nervous
system. 30% of RCC patients have a paraneoplastic syndrome.

There are many types of paraneoplastic syndrome, often categorized on the basis of the predominant organ system affected.

Mechanistically, they result from either:

-secretion of biologically active substances
-alterations of immunity e.g. auto-immune syndromes, immune complex disease

In some cases no mechanism can be determined. In the case of our patient, the erythrocytosis is likely the result of ectopic
erythropoietin secretion by the tumor cells. This can be found in up to 10% of cases. There are two main mechanisms for the
hypercalcemia; humoral hypercalcemia of malignancy (HHM) due to secretion of parathyroid-hormone-related-peptide (PTHrP) and
osteolytic hypercalcemia. HHM is the most common paraneoplastic syndrome in patients with RCC, occurring in 20% of cases.

Suggested References
Sacco E, Pinto F, Sasso F, et al. Paraneoplastic syndromes in patients with urological malignancies. Urol Int 2009; 83: 1-11.
 
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