NOTES NOTES HYPERPARATHYROIDISM & HYPOPARATHYROIDISM GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ An imbalance of parathyroid hormone (PTH) due to overproduction or underproduction by the parathyroid gland resulting in impaired regulation of calcium and other electrolytes Hyperparathyroidism ▪ ↑ PTH → ↑ bone resorption and ↑ renal reabsorption of calcium → ↑ serum calcium levels → asymptomatic or symptomatic hypercalcemia Hypoparathyroidism ▪ ↓ PTH → ↓ serum calcium → symptomatic hypocalcemia RISK FACTORS ▪ Hyperparathyroidism ▫ Genetic mutations, chronic kidney disease, ↓ vitamin D intake/absorption, hyperplasia of parathyroid glands ▪ Hypoparathyroidism ▫ Most commonly iatrogenic cause due to accidental removal or damage to parathyroid blood supply during thyroid surgery COMPLICATIONS ▪ Hyperparathyroidism ▫ Osteoporosis, osteitis ﬁbrosa cystica, nephrolithiasis, keratopathy, symptomatic hypercalcemia (e.g. hypertension, cardiac arrhythmias) ▪ Hypoparathyroidism ▫ Symptomatic hypercalcemia (e.g. respiratory paralysis, cardiac arrhythmias) 102 OSMOSIS.ORG SIGNS & SYMPTOMS ▪ See individual disorders DIAGNOSIS LAB RESULTS ▪ Measure serum PTH, calcium, phosphate, magnesium, 25-hydroxyvitamin D, urine calcium OTHER DIAGNOSTICS ▪ Genetic testing TREATMENT MEDICATIONS ▪ Hyperparathyroidism ▫ Vitamin D analogs, calcimimetics, bisphosphonates ▪ Hypoparathyroidism ▫ IV calcium gluconate (acute), vitamin D analogs, synthetic PTH, thiazide diuretics (↓ renal calcium excretion) SURGERY ▪ Hyperparathyroidism ▫ Partial/complete parathyroidectomy; radiofrequency ablation OTHER INTERVENTIONS ▪ Hyperparathyroidism ▫ Physical activity to ↓ bone resorption, maintain hydration to ↓ nephrolithiasis, vitamin D supplements ▪ Hypoparathyroidism ▫ Calcium, magnesium, and vitamin D supplements
HYPERPARATHYROIDISM NOTES osms.it/hyperparathyroidism PATHOLOGY & CAUSES TYPES Primary ▪ Parathyroid gland creates PTH independently of calcium levels, does not respond to normal feedback mechanisms Secondary ▪ Parathyroid gland hyperplasia, excess parathyroid hormone secreted in response to chronic hypocalcemia ▪ Impaired kidney function; kidneys do not ﬁlter phosphate properly into urine, make insufﬁcient calcitriol ▫ AKA renal osteodystrophy (bone pain, fracture) ▪ Altered calcium, phosphate levels → increased parathyroid hormone levels → bone resorption Tertiary ▪ Develops in individuals with secondary hyperparathyroidism for many years, often due to hyperplasia of parathyroid glands ▪ Autonomous secretion of PTH separately from blood calcium levels ▫ Even if causes of secondary hyperparathyroidism (e.g. renal transplant) corrected, increased PTH persists RISK FACTORS Primary ▪ Genetic mutations ▫ Multiple endocrine neoplasia (MEN) syndrome COMPLICATIONS Primary ▪ Brown tumors, large bone cysts (due to high osteoclast activity) SIGNS & SYMPTOMS ▪ “Stones, thrones, bones, groans, and psychiatric overtones”; see mnemonic Primary, tertiary ▪ Slower muscle contractions caused by less excitable neurons secondary to hypercalcemia Secondary ▪ Bone resorption/renal osteodystrophy; calciﬁcation of blood vessels, soft tissues MNEMONIC Signs and symptoms of hyperparathyroidism Stones: calcium-based kidney stones, gallstones Thrones: toilet; polyuria (frequent urination) from impaired sodium, water reabsorption Bones: pain from chronic hormone-driven demineralization Groans: constipation, muscle weakness Psychiatric overtones: depressed mood, confusion OSMOSIS.ORG 103
DIAGNOSIS LAB RESULTS Primary ▪ High total serum calcium (hypercalcemia), low phosphate (hypophosphatemia), high PTH valve during diastole ▪ Hypercalciuria from excess calcium loss through urine, may cause dehydration ▪ Serum 25-hydroxyvitamin D ▫ Determine type Secondary ▪ Low calcium, high phosphate, low vitamin D Tertiary ▪ Normal-high calcium, high PTH, low vitamin D Figure 17.1 An ultrasound of the neck demonstrating a large parathyroid adenoma situated posteriorly and to the right of the right thyroid lobe. The skin surface is at the top of the image. TREATMENT MEDICATIONS Primary, tertiary ▪ Calcimimetics ▫ Drugs that imitate calcium by attaching to CaSR on parathyroid cells ▫ If surgery not an option Secondary ▪ Hyperphosphatemia ▫ Phosphate binders ▪ Vitamin D supplements ▫ Increase calcium absorption, reduce PTH synthesis ▪ Calcitriol, vitamin D analogs (doxercalciferol, paricalcitol) ▫ Suppress PTH levels ▪ Calcimimetics ▫ Modulate CaSR → increase sensitivity of serum calcium → decrease PTH levels Tertiary SURGERY ▪ Remove abnormal parathyroid glands 104 OSMOSIS.ORG Figure 17.2 A X-ray image of the forearm demonstrating a brown tumor of the distal radius in an individual with hyperparathyroidism.
Chapter 17 Hyperparathyroidism & Hypoparathyroidism HYPOPARATHYROIDISM osms.it/hypoparathyroidism PATHOLOGY & CAUSES SIGNS & SYMPTOMS ▪ Underproduction of parathyroid hormone (PTH); hypo- = under/low ▪ No parathyroid hormone → ↓ bone resorption, ↓ renal calcium reabsorption, ↓ intestinal calcium reabsorption → hypocalcemia, hyperphosphatemia → ↑ cell excitability → tetany, paresthesias, seizures, arrhythmias ▪ Asymptomatic/life-threatening ▫ Degree, duration of hypocalcemia ▫ Muscular dysfunction → respiratory paralysis → death ▪ ECG changes ▫ Prolonged QT, ST ▫ Torsades des pointes ▫ Atrial ﬁbrillation CAUSES Acute ▪ Muscular spasms/cramps → tetany → Chvostek, Trousseau signs ▪ Perioral numbness, paresthesias, seizures Autoimmune disorders Magnesium deﬁciencies Latrogenic ▪ Most common ▪ Thyroid/parathyroid surgery/radiation Hereditary abnormalities ▪ DiGeorge syndrome (DGS) ▪ Autosomal dominant hypoparathyroidism ▪ Albright hereditary osteodystrophy (pseudohypoparathyroidism) ▫ Kidney resistance to PTH, increased PTH Chronic ▪ Extrapyramidal movements → basal ganglia calciﬁcations ▫ Dystonias, parkinsonism, athetosis, hemiballismus, oculogyric crisis ▪ Cataracts ▪ Dermatologic manifestations ▫ Dry, coarse skin; brittle nails; patchy alopecia OSMOSIS.ORG 105
Figure 17.3 Dry, brittle nails are a dermatologic manifestation of chronic hypoparathyroidism. DIAGNOSIS LAB RESULTS ▪ Hypocalcemia, low serum PTH ▪ Hypercalciuria OTHER DIAGNOSTICS ▪ Medical history of thyroid surgery/radiation TREATMENT MEDICATIONS ▪ ▪ ▪ ▪ 106 OSMOSIS.ORG IV calcium gluconate (severe cases) Oral calcium (mild-moderate cases) Vitamin D supplementation Synthetic PTH