Hyperparathyroidism

Background

Causes

• Parathyroid adenoma (most common), parathyroid hyperplasia, parathyroid carcinoma
• Milk alkali syndrome
• Granulomatous
• Secondary hyperparathyroidism (response to hypocalcemia)
• Tertiary hyperparathyroidism due to CKD

Clinical Features

• Asymptomatic, often
• Hypercalcemia features if primary
• Hypocalcemia features if secondary

Symptoms of hypercalcemia

Mnemonic: Stones, Bones, Groans, Moans, Thrones, Psychic Overtones

• "Stones"
  • Renal calculi
  • Renal failure
• "Bones"
  • Bone pain/destruction
• "Groans"
  • Abdominal pain, vomiting
  • Dehydration
  • Pancreatitis
• "Thrones"
  • Polyuria/polydipsia (Renal insufficiency)
  • Constipation
• "Psychic Overtones"
  • Lethargy/confusion/hallucinations

Symptoms of hypocalcemia

• Paresthesias (mouth, fingertips)
• ↑ DTRs
• Cramps
• Weakness
• Confusion
• Seizures
• Chvostek/Trousseau signs, Tetany
• Hallucinations
• Laryngospasm
• Bronchospasm
• Cardiac dysrhythmias

Differential Diagnosis

Causes of Hypercalcemia

• Addison's disease
• Calciphylaxis
• Excess vitamin D
• Hypercalcemia of malignancy
• Hyperparathyroidism
• Hyperthyroidism
• Hypothyroidism
• Lithium
• Milk-alkali syndrome
• Paget disease
• Sarcoidosis
• Thiazide diuretics

Jaw Spasms

• Acute tetanus
• Akathisia
• Conversion disorder
• Drug toxicity (anticholinergic, phenytoin, valproate, carbamazepine)
• Dystonic reaction
• Electrolyte abnormality
  • Hypocalcemic tetany
  • Magnesium
• Mandible dislocation
• Meningitis
• Peritonsillar abscess
• Rabies
• Seizure
• Strychnine poisoning
• Stroke
• Temporomandibular disorder
• Torticollis

Evaluation

• Evaluate for underlying etiology/alternate diagnoses of symptoms
• PTH- elevated
• Calcium- elevated if primary, low if secondary
• Phosphate- low in primary, high in secondary
• Alk phos- elevated

Management

Hypocalcemia

Avoid empiric treatment in patients taking digoxin due to risk for Stone Heart

• Asymptomatic
  • Calcium gluconate 1 gm PO Q6hrs
  • Vitamin D (calcitriol) 0.2 mcg BID
• Symptomatic
  • Calcium gluconate/calcium chloride 10mL of 10% soln IV over 10min
• Correct hypomag at same time (otherwise PTH is inhibited)
• Avoid phenothiazine antipsychotics (may precipitate extrapyramidal symptoms)
• Avoid furosemide (may worsen hypocalcemia)

Hypercalcemia

Asymptomatic or Ca <12 mg/dL

• Does not require immediate treatment
• Advise to avoid factors that can aggravate hypercalcemia (thiazide diuretics, Li, volume depletion, prolonged inactivity, high Ca diet)

Mildly symptomatic Ca 12-14 mg/dL

• May not require immediate therapy; however, an acute rise may cause symptoms necessitating treatment as described for severe hypercalcemia (see below)

Symptomatic or Severe hypercalcemia (Ca >14 mg/dL)

• Patients are likely dehydrated and require saline hydration as initial therapy

Hydration

• Isotonic saline at 200-300 mL/hour; adjust to maintain urine output at 100-150 mL/hour

Calcitonin

• Consider adding calcitonin 4 units/kg SC or IV q12hr in patients w/ Ca >14 mg/dL (3.5 mmol/L) who are also symptomatic (lowers Ca w/in 2-4hr)
• Tachyphylaxis limits use long term, but is a great choice for emergent cases

Bisphosphonates

Give for severe hypercalcemia due to excessive bone resorption (lowers Ca within 12-48hr)

• Pamidronate 90mg IV over 24 hours OR
• Zoledronate 4mg IV over 15 minutes
• Caution in renal failure, though bisphosphonates have been safely used in pts with pre-existing renal failure

Electrolyte Repletion

• Correct hypokalemia
• Correct hypomagnesemia

Diuresis

• Furosemide is NOT routinely recommended
• Only consider in patients with renal insufficiency or heart failure and volume overload

Dialysis

Consider if patient:

• Anuric with Renal Failure
• Failing all other therapy
• Severe hypervolemia not amenable to diuresis
• Serum Calcium level >18mg/dL

Corticosteroids

Decrease Ca mobilization from bone and are helpful with steroid-sensitive tumors (e.g. lymphoma, MM)

• Prednisone 60mg PO daily

See Also

• Hypercalcemia
• Hypocalcemia