Calcium (Ca++)

Calcium (Ca++)

1. Hypocalcemia

   • Symptoms
     • Positive Chvostek and Trousseau's signs.
     • CV: heart rate high or low; weak thready pulse; Severe: hypotension, prolonged ST and QT intervals
     • NM: Paresthesias of hands and feet, muscle twitching, cramps, spasms; also tingling lips, nose, ears. May signal onset of NM overstimulation and tetany.
     • GI: Increased peristalsis, hyperactive bowel sounds, cramping, diarrhea
     • SK: Osteoporosis, loss of height, curvatures; common with chronic hypocalcemia
   • Medical Interventions
     • Supplemental Ca++: PO or IV
     • Correction of underlying cause
     • AlOH and Vit D to increase absorption
     • Mag Sulfate or muscle relaxants to decrease nerve and muscle responses.
     • Labs
   • Nursing Interventions
     • Seizure Precautions: low bed, siderails up
     • Nutrition therapy: a high-Ca++ for mild hypocalcemia and chronic conditions
     • Reduce Environmental Stimuli
     • Emergency equipment on hand (suctioning, ET tray, emergency drugs).
     • Initiate/Maintain IV access.
     • Monitor frequently for s/s of effective treatment or worsening condition.
   • Serum Value <9.0 mg/dL
   • Etiology
     • Actual Deficits = reduction in total body Ca++.
       • Ex: Inadequate intake of Ca++ or Vit D, malabsorption (Celiac, Crohn's), ESRD, Diarrhea, Steatorrhea, wound drainage - esp. GI
     • Relative Deficits = total body Ca++ is normal, serum Ca++ is low.
       • Ex: Hyperproteinemia, alkalosis, citrate, Ca++ chelators, penicillamine, acute pancreatitis, hyperphosphatemia, immobility, parathyroid removal/destruction.

2. Hypercalcemia

   • Symptoms
     • CV: First increases HR and BP; Severe hypercalcemia depresses HR; dysrhythmias; increased and unnecessary clot formation, shown by s/s of impaired blood flow to tissues (cap refills, temperature inequality, color changes).
     • NM: Severe muscle weakness, decreased deep tendon reflexes, altered LOC, psychiatric problems.
     • GI: Decreased peristalsis, constipation, anorexia, N/V, hypoactive/absent bowel sounds, abdominal distention.
   • Medical Interventions
     • D/C Ca++ or Vit D containing drugs.
     • Fluid Volume Replacement (IV NS to increase excretion of Ca++).
       • Labs
     • Change from thiazide diuretics to those that increase excretion of Ca++.
     • Ca++ chelators or binders, phosphorus, calcitonin, biphosphonates, aspirin, NSAIDs.
     • CARDIAC MONITORING!
     • Dialysis for severe and life-threatenting hypercalcemia, usually hemodialysis or blood ultrafiltration.
   • Nursing Interventions
     • CARDIAC MONITORING!
       • Watch for changes in HR and Rhythm, and changes in T waves and QT interval.
       • Monitor frequently, compare with baseline.
       • Cardiac changes are most life threatening!
     • Frequent assessment of NM status
       • Assess LOC, DTR's, skeletal muscle strength.
     • Assess for slowed or impaired blood flow (calf circ, cap refills, pallor, temperature changes), esp. in BLE, pelvic region.
     • Monitor frequently for s/s of effective treatment or worsening condition.
   • Serum Value >10.5 mg/dL
   • Etiology:
     • Actual Excess: increase in total body Ca++.
       • Ex: Excess intake of Ca++ or Vit D, Kidney failure, use of Thiazide diuretics.
     • Relative Excess: total body Ca++ is normal, serum Ca++ is high.
       • Ex: Hyperparathyroidism; malignancies (esp of lung, breast, and bone); indirect resorption; hyperthyroidism; immobility; use of glucocorticoids; dehydration (hemoconcentration).

3. Normal Range (Free/Unbound Ca++ in blood): 9.0-10.5 mg/dL

   • Any change in Ca++ can have major effects on function because of the relatively low serum levels

4. Importance in the Body

   • Functions are closely r/t P and Mg
   • Enters the body through dietary intake (esp. dairy!) and absorption is facilitated by Vit D.
     • Dairy products, tofu, leafy greens, and almonds are high in calcium.
   • Absorbed in the intestinal tract, stored in the bones, and regulated by PTH (parathyroid hormone) and TCT (thyrocalcitonin).
     • PTH increases serum levels by releasing free Ca++ from bone storage, stimulating Vit D activation to increase intestinal absorption, inhibiting kidney excretion and stimulating kidney reabsorption of Ca++.
     • PTH is inhibited when Ca++ is high in the blood, and TCT is excreted by the thyroid. TCT inhibits bone resorption, inhibits Vit D assisted intestinal uptake, and increases the kidney excretion of Ca++.
   • Excitable membrane stabilizer, regulates the depolarization and generation of AP's in the CNS and PNS.
     • Low serum levels make excitable membranes MORE excitable because they increase the movement of Na+ across the membranes.
     • High serum levels make excitable membranes LESS excitable, requiring MORE stimuli.Usually this affects the heart, skeletal muscles, and intestinal smooth muscles initially and predominantly, but affects all systems.
     • Maintains bone strength, activates enzymes,facilitates skeletal and cardiac muscle contraction.
     • Controls impulse transmission in the CNS and PNS.
     • Remember Ca++ channels from Phys?
   • Utilized by many of enzymes involved in blood clotting

5. Ignaviticus, D., & Workman, M. L. (2013). Medical-surgical nursing: Patient-centered collaborative care. (7th ed., pp. 187-191). St. Louis, Missouri: Elsevier-Saunders.

6. AH 1 F&E Presentation

   • Barb, Jenny, Tandi
   • 05/13/2013