Paraneoplastic Syndromes
Bailey Decoursey
Justin Lo
Hypercalcemia of Malignancy
Background
- Caused by PTHrP production, osteolytic lesions, and/or rarely exogenous Vit D
- PTHrP: breast cancer, NSCLC (squamous)
- Osteolysis: multiple myeloma, Breast Cancer;
- Exogenous vit D: lymphoma
Evaluation
- Correct [Ca2+] for hypoalbuminemia: [Ca2+] + 0.8 x (4.0 – albumin)
- Send basic hyperCa+2 work-up: PTH, vit D, etc (see “Hypercalcemia” section)
- PTHrP is called “Parathyroid Hormone-related Peptide-ARUP” in Epic
Management
- First line: IVF without calcium such as Normosol; goal urinary output of 150-200 mL/hr
- Strict I/Os: cautious IV fluids in pts with cardiac or renal dysfunction
- Add Furosemide if hypervolemic (do not empirically start)
- Second line: zoledronic acid 4mg IV (takes 24-48 hours to see effect)
- AMS or severe hypercalcemia (>14mg/dL): calcitonin 4 IU/kg (requires attending approval)
SIADH
Background
- Euvolemic hypotonic hyponatremia with urine sodium >20 and typically urine Osm >100
- Associated with: SCLC (most common), head/neck cancers, breast cancer
- See "Hyponatremia” section for additional information
Management
- Free water restriction to 800mL/day
- Refractory: salt supplementation (e.g. salt tabs) ± loop diuretic
Carcinoid Syndrome
Background
- Episodic flushing, diarrhea, wheezing/SOB due to secretion of histamine & serotonin
- Most common: Neuroendocrine tumors, GI (often with mets to liver and lung)
Evaluation
- Urine: UR 5-HIAA (ARUP)
- Imaging to identify tumor(s): CT C/A/P
Management
- Short-term treatment: subQ or IV octreotide (see UpToDate for dosing)
- Antidiarrheals (Imodium, Lomotil) to slow transit
- Long-term treatment: depot (IM) forms of octreotide and lanreotide
- Refractory: Discuss with oncologist and PharmD about Telotristat Ethyl (inhibitor of tryptophan hydroxylase, FDA approved in combination with somatostatin analog (SSA) when SSA is not sufficient to control carcinoid symptoms).
Autoimmune Encephalitis, Encephalomyelitis, and Myelitis
Background
- Encephalopathy (limbic or brainstem) ± myelitis (limb ataxia, sensory deficits)
- Associated with small cell lung cancer and checkpoint inhibitor therapy
Evaluation
- LP: make sure to order CSF oligoclonal bands and CSF IgG index
- “Paraneoplastic AutoAb Eval-MAYO” (add "CSF" to the front of the order name if for LP)
- NMDA-R can be ordered as a standalone test
- CT head
- EEG if concern for subclinical seizures
Management
Consult Neurology for possible immunosuppressive therapy (steroids, IVIG)
Lambert-Eaton Myasthenic Syndrome (LEMS)
Background
- Muscle weakness due to autoantibody against calcium channels resulting in ↓ ACh release
- Associated with SCLC (most common) & lymphoma
- See “Myasthenia Gravis (MG) and Lambert-Eaton Myasthenic Syndrome (LEMS)” section in Neurology