Parathyroid Disorders
Key Points
- PTH (parathyroid hormone) raises serum calcium; calcium and phosphorus have an inverse relationship.
- Hyperparathyroidism: elevated PTH → hypercalcemia → “Bones, Stones, Groans, Thrones” mnemonic.
- Hypoparathyroidism: deficient PTH → hypocalcemia → tetany, Chvostek’s sign, Trousseau’s sign.
- Most common cause of hypoparathyroidism is inadvertent removal of parathyroid glands during thyroidectomy.
- Post-thyroidectomy nursing priority: monitor airway (hematoma) AND watch for hypocalcemia (hungry bone syndrome).
Pathophysiology
The four parathyroid glands (on the posterior thyroid surface) secrete PTH in response to low serum calcium. PTH increases calcium by:
- Stimulating osteoclast bone resorption
- Increasing renal calcium reabsorption and phosphate excretion
- Activating vitamin D → enhanced intestinal calcium absorption
Inverse relationship: Calcium and phosphorus move in opposite directions. Without PTH (hypoparathyroidism), phosphate rises while calcium falls.
Hyperparathyroidism
| Feature | Finding |
|---|---|
| Serum calcium | Elevated (hypercalcemia) |
| PTH level | Elevated |
| Serum phosphorus | Decreased |
| Most common cause | Parathyroid adenoma (tumor) |
| Secondary cause | Chronic kidney disease or vitamin D deficiency (compensatory PTH rise) |
| Treatment | Parathyroidectomy; IV fluids; calcium chelators; furosemide (promotes renal calcium excretion) |
Classic mnemonic — “Bones, Stones, Groans, Thrones (and Psychic Moans)“:
| Category | Manifestations |
|---|---|
| Bones | Bone pain, muscle weakness, decreased bone density, spontaneous fractures |
| Stones | Nephrolithiasis (kidney stones) from elevated urinary calcium |
| Groans | Nausea, vomiting, constipation, abdominal pain, anorexia, pancreatitis |
| Thrones | Polyuria, polydipsia (nephrogenic diabetes insipidus–like pattern) |
| Psychic Moans | Depression, fatigue, confusion, memory loss, drowsiness |
| Cardiac | Dysrhythmias, hypertension |
Hypoparathyroidism
| Feature | Finding |
|---|---|
| Serum calcium | Decreased (hypocalcemia) |
| PTH level | Decreased |
| Serum phosphorus | Elevated |
| Most common cause | Inadvertent removal/damage to parathyroid glands during thyroidectomy |
| Other causes | Autoimmune, neck surgery, congenital, PTH resistance |
| Treatment | Calcium supplements, calcitriol (active vitamin D), low-phosphorus diet, phosphate binders when phosphorus remains elevated |
Nursing Assessment
NCLEX Focus
Two classic bedside signs of hypocalcemia (hypoparathyroidism):
- Chvostek’s sign: Tap the facial nerve (CN VII) anterior to the ear → involuntary facial twitching = positive
- Trousseau’s sign: Inflate BP cuff above systolic for 3 minutes → carpal spasm = positive (latent tetany)
Hypocalcemia symptoms (decreasing membrane stability → neuromuscular hyperexcitability):
- Numbness and paresthesia (toes, fingers, perioral)
- Muscle cramps and spasms
- Tetany — involuntary muscle contraction
- Laryngospasm — life-threatening airway emergency
- Seizures
- Cardiac dysrhythmias
Hypercalcemia symptoms (increasing membrane stability → decreased neuromuscular responsiveness):
- Fatigue, weakness, confusion, depression
- Constipation, nausea
- Kidney stones
- Pathological fractures
Nursing Interventions
Hyperparathyroidism (post-parathyroidectomy priorities):
- Monitor airway — hematoma risk → compression → obstruction (highest priority)
- Assess for hungry bone syndrome — sudden hypocalcemia as calcium is rapidly incorporated into bone after surgery; manifests as seizures, paresthesia, dysrhythmias
- Assess for possible laryngeal-nerve injury after surgery (voice/phonation changes)
- Monitor serum calcium, phosphorus, magnesium
- Fall and fracture precautions (decreased bone density)
Hypoparathyroidism:
- Administer IV calcium gluconate for severe symptomatic hypocalcemia
- Administer oral calcium supplements and calcitriol as ordered
- Maintain seizure precautions; prepare for emergency airway management (laryngospasm)
- Monitor Chvostek’s and Trousseau’s signs
- Dietary education: high-calcium and high-vitamin D foods, low-phosphorus foods
- Monitor periodic calcium, phosphorus, and renal-function trends during chronic replacement therapy
- Titrate chronic replacement toward the low-normal serum calcium range to reduce kidney-stone risk while controlling paresthesia and cramps
Post-Thyroidectomy Hypocalcemia
Within 24–48 hours post-thyroidectomy, monitor for perioral numbness, tingling in extremities, muscle cramps, and positive Chvostek’s/Trousseau’s signs — early indicators of inadvertent parathyroid removal. Keep IV calcium gluconate at the bedside.
Related Concepts
- calcium-balance-disorders — Hypercalcemia and hypocalcemia management principles.
- thyroid-disorders — Thyroidectomy is the leading cause of hypoparathyroidism.
- serum-calcium — Lab interpretation and normal reference ranges.
- endocrine-system — Feedback regulation of PTH and calcium homeostasis.
- kidney-disease — CKD is a leading cause of secondary hyperparathyroidism.
Self-Check
- A nurse taps the patient’s face anterior to the ear and observes facial twitching. What sign is this, and what electrolyte imbalance does it indicate?
- What is the most common cause of hypoparathyroidism, and what is the nursing priority in the first 24 hours after surgery?
- Which diuretic is used to treat hypercalcemia in hyperparathyroidism, and why?