7901 Clinical Challenges Of Paraneoplastic Endocrine Metabolic Syndromes: An Illustrative Example

Abstract Disclosure: S. Shankar: None. S.S. Sundar: None. M.S. Vaishnav: None. K. Thummala: None. L. Lekkala: None. S. Srikanta: None. K. Muniraj: None. T. Deepak: None. R.B. Vijay: None. V. Nath: None. C. Siddlingappa: None. P. Ravikumar: None. M.D. Chitra: None. Introduction: Paraneoplastic endocrine syndromes result from aberrant production by tumors of protein hormones, hormone precursors, or hormone like substances. In patients who are already receiving treatment for cancer, the onset of a paraneoplastic syndrome may be an indication of progression or relapse. Clinical Case: 2021: Age 81 female (hypertension). Carcinoma rectum; S/P surgery, colostomy, chemotherapy and radiotherapy. 2023: Palliative care, due to progressive metastatic (hepatic, pulmonary, bone) malignancy. 2023 Aug: Hospital admission for generalized weakness, not able to walk, severe pain and low-grade fever 10 days. A: Paraneoplastic Hyponatremia: Evaluation: S Sodium= 127, 129, 129, 137, 134 mmol/L (134-145); Spot urine sodium= 65 mmol; S Uric acid= 3.5 mg/dL (4.4-7.6); S Cortisol 8 am= 15.5 (6.7-22.6); T3 total= 0.34 ng/mL (0.97-1.69), T4 total= 6.87 mcg/dL (5.5-11), TSH= 1.87 mIU/mL (0.46-4.68); LH= 0.35 mIU/mL (16-54); FSH= 1.9 mIU/mL (23-116); S calcium= 8.9 mg/dL (8.4-10.2); S Phosphorus= 2.31mg/dL (2.5-4.5) Diagnosis: Possible paraneoplastic ADH secretion/ SIADH; pain/ narcotics-induced hypothalamic ADH secretion. Treatment: Fluid restriction, liberal salt intake, 3% saline; oral sodium bicarbonate and tolvaptan; tapentadol. B: Paraneoplastic Leukemoid reaction: Evaluation: Total leucocyte count= 29960, 36670, 44130, 58450 cells/mm3 (4000-11,000); Differential count: Neutrophils= 85-94%; Lymphocytes= 10-4%; CRP= 93.7, 24.0 mg/dL (<0.3); Procalcitonin= 0.097, 0.083 ng/mL (<0.1); Ruled out significant sepsis; no obvious laboratory or imaging evidence of any infectious or leukemic etiology. Diagnosis: Progressive leucocytosis due to Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) secretion from various neoplasms has been reported in literature. Treatment: Empirical antibiotic coverage. C: Paraneoplastic Hypokalemia: Evaluation: S Potassium= 3.3, 3.4, 3.7, 2.9, 3.0 mmol/L (3.5-5.1). Diagnosis: Hypokalemia likely due to (in vivo and in vitro) intracellular potassium uptake by rapidly proliferating leukocytes (and neoplasm- primary and metastatic). (Ectopic ACTH secretion / ruled out). Therapy: IV and oral potassium supplements. D: Paraneoplastic Fever: Cytokines (e.g., tumor necrosis factor and interleukin-1) release from tumor cells or infiltrating mononuclear cells. Clinical Lessons: Endocrine paraneoplastic syndromes can complicate patient’s clinical course, response to treatment, impact prognosis and even be confused as metastatic spread or another “non-existent” clinical entity. They can precede, occur concomitantly or present at later stage of tumour development. Recognition of the diverse clinical manifestations improves clinical outcomes (earlier cancer diagnosis, better quality of life, optimal tumour-directed therapy or decision towards non-aggressive focussed palliative care). Presentation: 6/2/2024