questions 5

Hyperparathyroidism

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Topic updated on 08/09/17 11:25am

Snapshot
  • 55-year-old woman has hypercalcemia discovered as an incidental finding during normal routine physical examination. A hand radiograph is shown at right.
Introduction
  • Increased parathyroid hormone (PTH) production that may be of primary, secondary or tertiary causes
  • Pathophysiology
    • PTH indirectly stimulates osteoclasts by binding to its receptor on osteoblasts, inducing RANK-L and M-CSF synthesis
  • Epidemiology
    • occurs in 0.1% of the population
    • 90% result from a single adenoma
    • remaining 10% from parathyroid hyperplasia
    • parathyroid carcinoma accounts for less than 1% of all cases
Classification
  • Primary 
    • typically the result of hypersecretion of PTH by a parathyroid adenoma/hyperplasia
    • may result in osteitis fibrosa cystica
      • breakdown of bone
      • common involves the jaw
  • Secondary
    • secondary parathyroid hyperplasia as compensation from hypocalcemia or hyperphosphatemia
      • ↓ gut Ca2+ absorption
      • ↑ phosphorous
    • associated conditions
      • chronic renal disease
        • renal disease causes hypovitaminosis D
          • leads to ↓ Ca2+ absorption 
      • renal osteodystrophy
        • bone lesions due to secondary hyperparathyroidism 
  • Tertiary
    • parathyroid glands become dysregulated after secondary hyperparathyroidism
      • secrete PTH regardless of Ca2+ level
     
    Serum Ca
    Serum Phos
    Serum PTH
    Primary
    Secondary
    normal or ↓
    Tertiary
Presentation
  • Symptoms
    • often asymptomatic
    • weakness
    • kidney stones ("stones")
    • bone pain ("bones")
    • constipations ("groans")
Evaluation
  • Serology
    • primary
      • hypercalcemia
      • ↑ PTH
    • secondary
      • hypocalcemia/normocalcemia 
      • ↑ PTH
    • malignancy
      • ↓ PTH
    • ↑ alkaline phosphatase
    • normal anion gap metabolic acidosis
      • ↓ renal reclamation of bicarbonate
  • Urinalysis
    • primary
      • hypercalciuria (renal stones)
      • ↑ cAMP
  • Radiograph
    • cystic bone spaces ("salt and pepper")
      • often in the skull
    • loss of phalange bone mass
      • ↑ concavity (see key image of this topic)
    • subperiosteal thinning (cortical resorption) 
  • EKG
    • shortened QT
Treatment
  • Operative
    • resect adenoma/hyperplastic glands
      • indications
        • primary hyperparathyroidism with adenoma
      • outcome
        • curative if present
  • Pharmacologic
    • hydration followed by furosemide
      • ↑ excretion of calcium
    • bisphosphonates
    • cinacalcet 
      • calcium mimetic that decreases PTH production in the parathyroid glands
Complications
  • Peptic ulcer disease
    • ↑ gastrin production stimulated by ↑ Ca2+
  • Acute pancreatitis
    • ↑ lipase activity stimulated by ↑ Ca2+
  • CNS dysfunction
    • anxiety, confusion, coma
    • result of metastatic calcification of the brain


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Qbank (3 Questions)

TAG
(M1.EC.14) A 52-year-old female presents to clinic complaining of sudden onset of flank tenderness that was fluctuating and radiating into her groin. Laboratory analysis reveals a serum calcium of 12.4 (normal 8.4-10.2) and a serum phosphorous of 2.5 (normal 2.7-4.5) and a chloride:phosphorous ratio >33. You suspect primary hyperparathyroidism. Which of the following mechanisms is responsible for the patient’s current condition? Topic Review Topic

1. PTH binding to receptors on osteoclasts
2. Parafollicular, or C-cell, synthesis of calcitonin
3. Increased RANK-L production
4. Decreased M-CSF production
5. Increased synthesis of osteoid by osteoblasts

PREFERRED RESPONSE ▶
TAG
(M1.EC.21) A 65-year-old female with chronic renal failure presents with recent onset of bone pain. Serum analysis reveals decreased levels of calcium and elevated levels of parathyroid hormone. One of the mechanisms driving the elevated PTH is most similar to that seen in: Topic Review Topic

1. End stage liver failure
2. Insufficient Ca intake
3. Parathyroid adenoma
4. Decreased functioning of the calcium-sensing receptor (CASR)
5. Sarcoidosis

PREFERRED RESPONSE ▶
TAG
(M1.EC.75) A 54-year-old female presents to her primary care physician with complaints of fatigue, constipation, and what the patient describes as "aching in her bones." Her medical history is significant for hypertension, well-controlled on lisinopril, and two prior kidney stones that both passed spontaneously without need for surgery. Vital signs are within normal limits, and physical exam is not significant for any notable findings. Preliminary lab work is ordered and reveals: calcium 11.6 mg/dL (normal range 8.5 - 10.9 mg/dL), phosphorus 2.1 mg/dL (normal range 2.4 - 4.1 mg/dL), and an elevated parathyroid hormone (PTH) level. Which of the following findings would most likely be expected on radiographic evaluation of this patient's hands? Topic Review Topic

1. Joint space narrowing at the proximal and distal interphalangeal joints
2. Osteoid matrix accumulation around bony trabeculae
3. Subperiosteal cortical thinning
4. Ulnar deviation of the metacarpophalangeal joints
5. Dense bone filling the medullary cavity of the phalanges and metacarpals

PREFERRED RESPONSE ▶
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