Question

A 65 yr old smoker reported to the hospital with a profound weight loss over the last six months and an intermittent dry cough. Based on the chest X-ray and other tumor marker analysis, he was diagnosedwith small-cell lung cancer. His physicians were aware that many small-cell lung cancers produce high levels of Anti-diuretic hormone (ADH). Therefore, they analyze the patient's electrolyte levels and note the following values Na (meq/L) K HCO3 (meq/L) BUN (mg/dL) - Osm СІ (meq/L) 98-108 Cr (mg/dL) 0.6-1.2 0.9 (meq/L) 3.5-5.5 3.6 Normal Patient 135-145 116 22-29 - 24 7-18 10 280-290 248 85 a. Does this patient show signs of electrolyte imbalance due to increased levels of ADH? b. Explain the biological reasoning behind the observed results. C. Explain the connection between patient's Na+ serum levels and serum osmolality seen here. d. What would be the water status of this patient-hyper, hypo or euveolemic? Where would it be reflected in the tests performed on the patient above?

Answer 1

a. Yes ,this patient shows signs of electrolyte imbalance as evidenced by low sodium , chloride and osmolarity .

b. The reason behind the observed results is ectopic release of ADH (SIADH).

3. Low sodium causes low osmolarity as water rushes into the cells

4. The water status is hyperveolemic as the sodium level in blood is decreased .