Hyperparathyroidism

Surgery

Causes:

• Primary hyperparathyroidism: is usually due to a parathyroid benign adenoma (75%) or parathyroid hyperplasia (20%). 1.0% have parathyroid carcinoma.

• Secondary hyperparathyroidism: is hyperplasia of the gland in response to hypocalcemia (e.g., in chronic renal failure).

• Tertiary hyperparathyroidism: autonomous secretion of parathormone occurs when the secondary stimulus has been removed (e.g., after renal transplantation).

• MEN syndromes: (type I (parathyroid adenoma, pancreatic islet cell tumors, pituitary adenoma) and type II (parathyroid adenoma, medullary thyroid cancer, pheochromocytoma)

• Ectopic parathormone production (e.g., from small cell lung cancer).

Pathology:

• Parathormone mobilizes calcium from bone,
• enhances renal tubular absorption and,
• with vitamin D, intestinal absorption of calcium.
• The net result is hypercalcemia.

Clinical features

• Older women, >40 years of age.
• Renal calculi or renal calcification – occurs in 20% of patients, polyuria (‘renal stones’).
• Bone pain or deformity, osteitis fibrosa cystica, pathological fractures (‘painful bones’).
• Muscle weakness, anorexia, intestinal atony, psychosis (‘psychic moans’).
• Peptic ulceration and pancreatitis (‘abdominal groans’).

Symptoms of hypercalcemia

Salt-and-pepper-spots-in-skull

Laboratory:

• High PTH

• Elevated serum Ca

• Low phosphate

• High Alkaline Phosphatase

• Low Mg

• High urinary Ca

• Elevated PTH in the setting of hypercalcemia.

• Serum calcium (specimen taken on three occasions with patient fasting, at rest and without a tourniquet). Body Ca:

  • 99% stored in the skeleton
  • 1% is free
    • ½ bound to proteins
    • ½ is free ionized (Active)

• Normal range 2.2–2.6 mmol/L. Calcium is bound to albumin and the level has to be ‘corrected’ when albumin levels are abnormal.

• May be decreased serum phosphate and elevated alkaline phosphatase

Radiology:

• DEXA: Wrist, spine, and hip
• KUB, IVP, CT (For renal stones)

DEXA: Dual Emission X-ray Absorptiometry Demineralization of long bones, Pathological fracture

Lytic lesions caused by hyperparathyroidism are called Brown tumors. The term “Brown tumor” is a misnomer because it is not a true neoplasm.

Management of Hypercalcemia

• Rehydration with intravenous saline until urine output of 100 /h.
• Intravenous lasix is given after rehydration.
• Serum potassium must also be replaced.
• Biphosphonate such as disodium pamidronate.
• Calcitonin
• Serum parathyroid hormone concentration must be measured urgently.
• Urgent parathyroidectomy.

Complications of parathyroidectomy:

• Post-op. bleeding

• Hematoma:

  • Pre tracheal (airway obstruction)
  • pre- platysmal

• Nerve injury

  • 1-2% permanent:
    • Recurrent laryngeal (hoarseness)
    • Superior laryngeal (loss of high pitched sound)

• Hypocalcemia

During surgery how will you confirm whether the tissue is parathyroid gland?

• Golden yellow color
• Put it in a cup of normal saline.
• Parathyroids usually sink but fat floats.
• Implant the parathyroid into the sternomastoid pocket or into the forearm

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Imaging

Two types:

• Primary
• Secondary: Occurs due to renal failure/renal osteodystrophy

Radiological features of hyperparathyroidism

• In hand, sub-periosteal bone resorption .This change usually happen in the middle phalanges, radial aspect in the 2nd or 3rd finger.
• Terminal tuft erosion.
• Salt and pepper skull

Sub-periosteal bone resorption

• Most useful sign
• Virtually Diagnostic
• Location

Subperiosteal bone resorption (straight arrow), resorption of the tip of the terminal phalanx and the altered bone architecture. Arterial calcification is also present (curved arrow).

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Ruger Jersey spine : secondary hyperparathyroidismz

Occurs due to renal failure/renal osteodystrophy prominent endplate densities at multiple contiguous vertebral levels to produce an alternating sclerotic-lucent-sclerotic appearance

On x-ray white margins with lucent central and vertical trabeculae, which is called( Ruger Jersey spine) these, (changes are due to renal dystrophy.

• Decreased bone density of the central portions (black area)
• Sclerotic vertebral end plates

(renal osteodystrophy). There are sclerotic bands running across the upper and lower ends of the vertebral bodies of the lumbar spine (arrows).

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Parathyroid

Hyperparathyroidism - Primary hyperparathyroidism

Routine imaging studies  Obtain in ALL patients with confirmed pHPT  to evaluate for renal and skeletal manifestations.

Skeletal evaluation

• Assess for osteoporosis
• Preferred modality: Dual-energy x-ray absorptiometry (DXA)
• Alternative: ***Vertebral x-ray ***

Renal imaging

• Assess for nephrolithiasis and/or nephrocalcinosis. 
• Options include abdominal CT without contrast, renal ultrasound, and abdominal x-ray.

Additional imaging studies Neck imaging

• For surgical planning to determine the location of the abnormal glands
• Options include ultrasound neck and nuclear imaging