II. Causes: General

  1. Most common causes of Hypercalcemia
    1. Malignancy
    2. Primary Hyperparathyroidism
  2. Malignancy
    1. See Hypercalcemia of Malignancy (mediated by PTH-Related peptide)
    2. Presents with rapid onset, low PTH Levels and weight loss, Night Sweats
    3. Breast Cancer with bone metastases
    4. Squamous Cell Lung Cancer
    5. Head and Neck squamous cell cancer
    6. Renal Cell Cancer
    7. Esophageal Cancer
    8. Skin Cancer
    9. Hematologic
      1. Multiple Myeloma
      2. Hodgkin's Lymphoma
  3. Paget's Disease of Bone
  4. Medications
    1. Thiazide Diuretics
    2. Lithium
    3. Vitamin A Toxicity
    4. Vitamin D Toxicity (e.g. 25-Hydroxyvitamin D2)
    5. Milk Alkali Syndrome
    6. Theophylline
    7. Synthetic PTH (Teriparatide, Abaloparatide)
  5. Hyperparathyroidism (PTH Dependent Hyperparathyroidism)
    1. Primary Hyperparathyroidism (most common cause)
    2. Multiple Endocrine Neoplasia (type 1 or 2A)
    3. Familial Hypocalciuric Hypercalcemia
    4. Lithium treatment
    5. Chronic Kidney Disease (Renal Osteodystrophy)
    6. Hyperparathyroidism - Jaw Tumor Syndrome
  6. Endocrine
    1. Vitamin D Deficiency (Secondary Hyperparathyroidism)
    2. Adrenal Insufficiency
    3. Thyrotoxicosis (Hyperthyroidism)
    4. Pheochromocytoma
    5. Acromegaly
  7. Other causes
    1. Familial Hypocalciuric Hypercalcemia
    2. Prolonged immobilization
    3. Granulomatous disease (Sarcoidosis, Tuberculosis, Histoplasmosis, Coccidioidomycosis)
    4. Williams Syndrome
    5. Jansen Disease (metaphyseal chondrodysplasia)

III. Findings: Symptoms and Signs

  1. Often asymptomatic
  2. Symptoms and Signs are related to Serum Calcium Levels
    1. Calcium > 11.5 mg/dl (2.9 mmol/L)
      1. Symptom onset
    2. Calcium > 13 mg/dl (3.2 mmol/L)
      1. Nephrocalcinosis
      2. Acute Renal Failure
    3. Calcium >14 mg/dl (3.5 mmol/L)
      1. Severe Hypercalcemia (or Parathyroid crisis)
  3. Cardiovascular
    1. Chest Pain
    2. Dyspnea
    3. Palpitations
    4. Syncope
    5. Hypertension
    6. Bradycardia
  4. Gastrointestinal
    1. Anorexia
    2. Constipation
    3. Epigastric Pain or other Abdominal Pain
    4. Dyspepsia
    5. Nausea
    6. Vomiting
    7. Pancreatitis
  5. Renal
    1. Polydipsia
    2. Polyuria
    3. Renal Colic or Flank Pain
    4. Renal Failure
  6. Neurologic
    1. Anxiety
    2. Confusion, Delirium
    3. Decreased Concentration
    4. Memory Loss
    5. Headache
    6. Fatigue
    7. Lethargy
    8. Weakness
  7. Psychiatric
    1. Anxiety
    2. Depressed Mood
    3. Emotional lability
  8. Musculoskeletal
    1. Bone pain
    2. Arthralgias
    3. Myalgias
    4. Pathologic Fractures
  9. Skin
    1. Pruritus (Metastatic calcification of skin)

IV. Complications: Stones, Bones, Moans, Psychic Groans

  1. Renal ("Stones")
    1. Nephrolithiasis (Calcium Oxalate)
    2. Nephrocalcinosis
      1. Metastatic calcification renal tubules
      2. Polyuria from loss of urine concentrating function
  2. Musculoskeletal ("Bones")
    1. Osteitis fibrosa cystica (Late finding)
      1. Bone cysts from subperiosteal bone resorption
      2. "Brown tumor" in jaw
    2. Pseudogout
      1. Calcium pyrophosphate - Positively birefringent
    3. Osteoporosis
  3. Gastrointestinal ("Abdominal Moans")
    1. Peptic Ulcer Disease
      1. Calcium stimulates Gastrin release
    2. Acute Pancreatitis
      1. Calcium activates phospholipases
    3. Constipation
      1. Most common gastrointestinal symptom
  4. Neuropsychiatric ("Psychic groans")
    1. Altered Level of Consciousness or Delirium
    2. Decreased concentration and memory
    3. Personality change
    4. Psychosis
    5. Major Depression
  5. Eye
    1. Band Keratopathy (Corneal calcification)
      1. Metastatic calcification in eye limbus
  6. Cardiovascular
    1. Cardiac Arrhythmia
    2. Diastolic Dysfunction
    3. Hypertension
      1. Hypercalcemia Vasoconstricts vessels

V. Imaging

  1. Calcified soft tissues

VI. Labs: Serum Calcium

  1. Total Serum Calcium increased
    1. Hypercalcemia: Total Serum Calcium > 10.5 mg/dl
    2. Severe Hypercalcemia (Hypercalcemic Crisis): Serum Calcium >14 mg/dl (>3.50 mmol/L)
  2. Confirmatory
    1. Ionized Calcium >5.6 mg/dl or
    2. Corrected Serum Calcium increased (corrected for Serum Albumin)

VII. Labs: Hypercalcemia Evaluation

  1. First-line
    1. Parathyroid Hormone
    2. 25-Hydroxyvitamin D
    3. Serum Magnesium
    4. Serum Creatinine
  2. Second-line: PTH level normal or high (PTH-dependent Hypercalcemia)
    1. Urine Calcium to Creatinine Ratio
      1. Decreased <0.01 in Familial Hypocalciuric Hypercalcemia
      2. Increased >0.01 in Primary Hyperparathyroidism, Hypercalcemia or Malignancy, MEN I
  3. Second-line: PTH level <20 pg/ml (PTH-independent Hypercalcemia)
    1. Parathyroid Hormone-related Peptide (PTHrp) increased
      1. Hypercalcemia of Malignancy
      2. Consider broad evaluation for malignancy
        1. Complete Blood Count
        2. Liver Function Tests
        3. Chest XRay
        4. Chest CT and Abdominal CT
        5. Protein electrophoresis (SPEP and UPEP)
        6. Bone Scan
        7. Mammogram
    2. 1,25 Dihydroxyvitamin D increased
      1. Lymphoma
      2. Granuloma (e.g. Sarcoidosis)
    3. 25-Hydroxyvitamin D (Calcitriol) increased
      1. Vitamin D Toxicity

VIII. Diagnostics: Electrocardiogram

IX. Evaluation

  1. General
    1. Primary Hyperparathyroidism and Hypercalcemia of Malignancy: 90% of cases
  2. Step 1: Confirm Hypercalcemia present (see labs above)
    1. Confirm Hypercalcemia with Ionized Calcium >5.6 mg/dl or Corrected Serum Calcium >10.5 mg/dl
    2. Immediate management for symptomatic or severe Hypercalcemia (Serum Calcium >14 mg/dl)
      1. See protocol below
  3. Step 2: Obtain history for potential causes
    1. See causes above
    2. Perform history (including diet, medications) and exam
    3. Consider Renal Osteodystrophy
    4. Eliminate potential causative medications (Thiazide Diuretics, Lithium)
  4. Step 3: Obtain intact Parathyroid Hormone (PTH) Level
    1. PTH low: Go to Step 4
    2. PTH normal or high (PTH-Dependent Hypercalcemia)
      1. Labs
        1. Urine Calcium to Creatinine Ratio (24 hour Urine Calcium and Urine Creatinine)
        2. Serum Creatinine
        3. Bone Mineral Density
        4. 25-Hydroxyvitamin D
      2. Urine Calcium to Creatinine Ratio <0.01
        1. Familial Benign Hypocalciuric Hypercalcemia (FBHH)
      3. Urine Calcium to Creatinine Ratio normal or high
        1. Causes
          1. Primary Hyperparathyroidism
          2. Recovery from Acute Tubular Necrosis
          3. Lithium
          4. Multiple Endocrine Neoplasia Type I (MEN I)
          5. Parathyroid carcinoma (severe Hypercalcemia and very high PTH)
        2. Approach
          1. Consult Endocrinology
          2. Exclude Multiple Endocrine Neoplasia Type I (MEN I)
          3. Manage Primary Hyperparathyroidism
            1. Medical management of Primary Hyperparathyroidism
            2. Parathyroidectomy if symptomatic, age <50, complications (e.g. renal)
  5. Step 4: PTH-Independent Hypercalcemia
    1. Assess for malignancy and endocrinopathy
    2. Careful history and examination for tumor
    3. Initial Labs
      1. Parathyroid Hormone-related Peptide (PTHrp)
        1. Increased in solid tumors (see Hypercalcemia of Malignancy)
        2. Consider broad evaluation for malignancy
          1. Complete Blood Count
          2. Liver Function Tests
          3. Chest XRay
          4. Chest CT and Abdominal CT
          5. Protein electrophoresis (SPEP and UPEP)
          6. Bone Scan
          7. Mammogram
      2. 1,25-dihydroxyvitamin D (Calcitriol) increased
        1. Obtain chest imaging (Chest XRay or Chest CT)
        2. Causes
          1. Lymphoma
          2. Granulomatous Disease (Sarcoidosis, Tuberculosis, Histoplasmosis, Coccidioidomycosis)
      3. 25-Hydroxyvitamin D Level increased
        1. Vitamin D Toxicity
    4. Other Labs to consider
      1. Alkaline Phosphatase: Increased with bone lysis
        1. Consider bone scan
      2. Protein electrophoresis (SPEP and UPEP)
        1. Monoclonal peak in Multiple Myeloma
      3. Endocrine Labs
        1. Thyroid Stimulating Hormone (Hyperthyroidism)
        2. Corticotropin Stimulation Test (Addison's Disease)
        3. Insulin-like Growth Factor 1 (Acromegaly)
    5. Reconsider medication causes of low PTH
      1. Thiazide Diuretics
      2. Vitamin D Toxicity
      3. Vitamin A Toxicity
      4. Milk-Alkali Syndrome
      5. Aluminum Intoxication

X. Management

  1. Identify and treat underlying cause
  2. Mild Hypercalcemia (Serum Calcium <12 mg/dl)
    1. Adequate Hydration (>2 Liters per day)
    2. Maximize mobility
    3. Diuretics if symptomatic
      1. Furosemide (Lasix) 40-160 mg/day
  3. Severe Hypercalcemia or Hypercalcemic Crisis (Serum Calcium >14 mg/dl, >3.50 mmol/L)
    1. Consider also in moderate symptomatic Hypercalcemia
    2. Normal Saline 2 to 4 Liters/day for 1-3 days
      1. Adjust to obtain 200 ml Urine Output per hour
      2. Exercise caution in Congestive Heart Failure
      3. Anticipate 1-3 mg/dl drop in Serum Calcium
    3. Additional measures if refractory after hydration
      1. Furosemide (Lasix) 10-20 mg every 1-2 hours as needed
        1. Most effective agent in Calcium elimination
      2. Calcitonin 4-8 IU/kg IM or SQ every 6 hours for 24 hours (up to 48 hours)
        1. Rapid onset, but weakest of the agents (do not use as monotherapy)
    4. Agents with specific indications
      1. Malignancy: Bisphosphonates
        1. Zoledronic acid (Zometa) 4 mg IV over 15 minutes
        2. Pamidronate (Aredia) 60-90 mg IV over 4 hours
      2. Vitamin D Toxicity, Lymphoma, Myeloma or Granuloma
        1. Hydrocortisone 200 mg IV qd for 3 days
    5. Other measures
      1. Oral Phosphate (Neutra-Phos) 250 mg PO q6 hours
      2. Denosumab
        1. Hu (2014) J Clin Endocrinol Metab 99(9):3144-52 +PMID: 24915117 [PubMed]
        2. Eremkina (2020) Endocr Connect 9(10):1019-27 +PMID: 33112830 [PubMed]
    6. Third line agents due to toxicity (avoid if possible)
      1. Plicamycin 10-25 mcg/kg/day IV over 6 hours x3 dose
        1. Cumulative liver, Kidney and Platelet toxicity
        2. Bisphosphonates are preferred over Plicamycin
      2. Gallium Nitrate (Ganite)
        1. Dose: 100-200 mg/m2 IV over 24 hours for 5 days
        2. Significant renal and Bone Marrow toxicity
    7. Refractory Cases
      1. Hemodialysis
        1. Loh (2014) Case Rep Crit Care +PMID: 24829837 [PubMed]

XI. Prognosis

  1. Hypercalcemia of Malignancy suggests terminal stages
    1. Implies Life Expectancy of days to weeks

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