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RENAL PATHOPHYSIOLOGY

SMALL GROUP DISCUSSION CASES

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Small Group Discussion 1 Case 1 A soldier who had been on desert maneuvers for several days is brought into the hospital in a confused state, BP 85/50, pulse 110, very dry skin and tongue, poor skin turgor. Please see pictures below. The following chemistries are documented: Serum Na 160 mEq/l, K 5.5 mEq/l, Cl 125 mEq/l, HCO3 28 mEq/l, osmolality 330 mOsm/kg. Urine osmolality 1000 mOsm/kg, urine Na 2 mEq/l, and 24-hour volume of 500 ml.

1.  Is this patient is able to concentrate his urine with respect to plasma? Why did he become hypernatremic?

2.  Which data provide clues to the pathogenesis of the hypernatremia?

3. What is the most appropriate therapy for the

hypernatremia? 4. How do you determine the amount and type of intravenous fluid given to any patient?

http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/17223.jpghttp://www.dental.mu.edu/oralpath/lesions/xerostomia/xerostomia3.jpg

Dry Mucous Membranes

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Case 2 A 50-year-old male with a long history of heavy alcohol consumption presents with swelling of the ankles and increasing abdominal girth. On examination his blood pressure is 100/70, pulse 95 and he is afebrile. He has signs of temporal muscle wasting, telangiectasia on the trunk, palmar erythema. Heart and lungs are normal. A spleen tip is palpated. Shifting dullness in the abdomen suggests ascites. There is 3+ pedal edema. (Please see pictures below.) His serum chemistries reveal Na 123 mEq/l, K 3.2 mEq/l, Cl 85 mEq/l, HCO3 25 mEq/l, Glucose 65 mg/dl, and BUN 10 mg/dl, Cr 1 mg/dL. 1.  What would you predict to find if you measured the sodium concentration and osmolality in a random sample

of urine (would the values be high or low)?

What are the mechanisms for this urine sodium concentration and urine osmolality in this patient?

http://medicine.ucsd.edu/clinicalmed/abdomen-ascites.jpg http://www.lumen.luc.edu/lumen/MedEd/medicine/pulmonar/images/leischne/Scan46.jpg

Caput MedusaAscites

4www.fotogeriatria.net/images/brazos/arana%20vascular%20brazo1.JPG

Pitting Leg Edema

Palmar Erythema

Telangiectasia

http://medicine.ucsd.edu/clinicalmed/extremities-massive-edema.JPG

http://www.lf2.cuni.cz/Projekty/interna/foto/002/i~000017.jpg

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Case 3 A 60-year-old man was hospitalized because of persistent left-sided headaches.

Physical examination revealed a well-appearing male with blood pressure of 110/70 and no orthostatic change. His mucous membranes were moist. There was no evidence of neck vein distension, rales, or edema. The remainder of the exam was within normal limits. A CT scan of his head showed a left parietal mass suggestive of a glioma.

Labs: Na 123 mEq/L

K 3.7 mEq/L Creatinine 0.6 mg/dl Cl 88 mEq/L Plasma osm = Posm 250 mOsm/kg HCO3 24 mEq/L Urine osm = Uosm 800 mOsm/kg BUN 4 mg/dl Urine Na = UNa 39 mEq/L

1.  What are the possible causes of hyponatremia in this

clinicalsetting?

2.  How does the urine osmolality and sodium concentration help in understanding the pathogenesis of this syndrome?

3.  What treatment would be appropriate for this patient?

4.  What other clinical situations would you see this syndrome?

http://www.id.yamagata-u.ac.jp/NeuroSurge/Image/glioma-Color.jpg

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Case 4

A 28-year-old man complains of gradual onset of nocturia, polyuria and polydipsia. His past medical history is unremarkable. His physical examination reveals no abnormalities.

The following laboratory data are obtained: Serum sodium is 140 mEq/L,

and CBC, rest of basic metabolic panel (Potassium, Chloride, Bicarbonate, BUN, Creatinine, and glucose) normal. Urine specific gravity 1.003, urine osmolality 60 mOsm/kg, UNa 10 mEq/l, and 24-hour urine volume 7200 cc.

1.  Do you think the high urinary volume is the cause or the

consequence of the polydipsia? 2.  What further diagnostic tests would you employ to address

the cause of the polyuria?