Disease Description (Causes and Symptoms)
- Definition: A condition in which the total blood calcium concentration is usually 10.5 mg/dL or higher, or ionized calcium is approximately 4.2 mg/dL or higher.
- Pathophysiology summary: Blood calcium concentration is regulated by parathyroid hormone (PTH), vitamin D (active form), calcitonin, and interactions among the kidneys, bones, and intestines. Hyperparathyroidism or malignant tumors (such as PTHrP secreted by tumors) are the most common causes, accounting for a substantial proportion of cases. Other possible causes include medications (excess vitamin D, thiazide, lithium, etc.), acute or chronic renal failure, and excessive bone resorption (bone metastases, multiple myeloma).
- Main symptoms: Nonspecific — fatigue, lethargy, loss of appetite, altered taste, nausea and vomiting, constipation, polyuria and dehydration, muscle weakness, changes in mental status (stupor, coma), cardiovascular abnormalities (arrhythmia, hypertension), pancreatitis, passage of kidney stones, etc. Symptoms vary depending on the blood calcium concentration and the rate of onset (mild <12 mg/dL is often asymptomatic; 12–15 mg/dL causes systemic symptoms; >15 mg/dL is severe).
Treatment Methods
- Emergency and general principles
- Rapid fluid administration: Intravenous normal saline (0.9% NaCl) to replenish intravascular volume and promote renal calcium excretion (first-line treatment). Continuous monitoring of electrolytes (especially K and Mg), body weight, and urine output is required.
- Diuretics: After rehydration, a loop diuretic (e.g., furosemide) may be used as needed to promote calcium excretion (however, it should be used only after correcting dehydration).
- Hemodialysis when fluid therapy is not possible due to severe renal failure or fluid overload (a low-calcium dialysate may be used).
- Medication treatment
- Calcitonin: Its effects develop rapidly, but resistance develops quickly, so it is used short term (within 48 hours). It is used for initial control of severe hypercalcemia.
- Bisphosphonates: Pamidronate, Zoledronic acid — effective by inhibiting bone resorption and standard treatments for malignancy-associated hypercalcemia (effects develop within 24–72 hours and last for a long time). Dose adjustment is necessary based on renal function.
- Glucocorticoids: Effective in vitamin D excess or granulomatous diseases (tuberculosis, sarcoidosis, etc.) by inhibiting vitamin D-mediated absorption.
- Denosumab: Considered when there is no response to bisphosphonates or when bisphosphonate use is limited by impaired renal function (especially in cancer-related cases).
- Treatment of the underlying cause: In cases of parathyroid adenoma, surgical removal; in cases of malignant tumors, etiologic treatment such as anticancer therapy, radiation, or surgery is crucial to the prognosis.
- Lifestyle management and precautions
- Drink sufficient fluids (follow the doctor's instructions). If fluid intake needs to be restricted despite having hypercalcemia, consult a healthcare professional.
- Do not stop medications that may worsen hypercalcemia, such as calcium or vitamin D supplements, thiazide diuretics, or lithium, on your own; adjust them after consulting your physician.
- Avoid excessive dairy product intake and a high-calcium diet.
- Hypocalcemia may occur after treatment (especially with bisphosphonate use), so calcium/vitamin D supplementation and follow-up testing are necessary.
Checklist Before an Outpatient Visit (Items to Prepare and Example Questions)
- Items/materials to prepare or submit
- List of all currently used medications (including prescription and nonprescription drugs and supplements): thiazide, lithium, calcium and vitamin D supplements, anticancer drugs, etc.
- Recently measured test results: total calcium, ionized calcium, albumin, PTH, 25(OH)D, creatinine and urinalysis, and previous ECGs (if available)
- Timing and course of symptom onset (when they began and factors that worsen or relieve them), changes in urine output, and changes in body weight
- Medical history: history of cancer, kidney disease, and endocrine diseases (parathyroid disease)
- Example questions to check before an outpatient visit
- When did the symptoms start recently? Have they remained constant or gradually worsened?
- Have you accurately written down all medications you are currently taking, including supplements?
- Have you had symptoms of dehydration (dry mouth, decreased urine output) or urinary abnormalities?
- Have you recently experienced changes in body weight, palpitations, impaired consciousness, or similar symptoms?
Examples of General Questions to Ask the Doctor
- What are the side effects of this medication, and what symptoms should I watch for while taking it?
- What is the most likely cause in my case, and what is the prognosis (risk of recurrence)?
- Are there any lifestyle changes I should make immediately (fluid intake, diet, or medications)?
Examples of Disease-Specific Questions
- If my blood PTH level is normal (or low/high), what does this result suggest about the cause of my hypercalcemia? What additional tests are needed?
- If this is malignancy-associated hypercalcemia, which treatment would you recommend first, a bisphosphonate or denosumab? What are the alternatives if my renal function is poor?
(Note: Total blood calcium should be corrected according to the albumin concentration, and the doctor will determine the exact diagnosis and treatment plan based on clinical test results and the individual's condition.)