Parathyroid glands
• 4 glands located near the thyroid
• PTH – polypeptide
• Regulates calcium homeostasis
• Defends against hypocalcemia
• Stimulates bone resorption by osteoclasts
• Stimulates renal tubular reabsorption of Ca
• Inhibits renal tubular reabsorption of phosphate
• Stimulates synthesis of the active form of vit D
Hypercalcemia
2.25 – 2.75 mmol/l
Causes:
primary hyperparathyroidism
Malignant diseases – osteolytic MT, hematologic
malignancies – producing PTHrp
Sarcoidosis, tbc, thyrotoxicosis
Drug induced – vit D,A, thiazide..
Immobilisation
Familial, ARI, CHRI
Primary hyperparathyroidism
-PTH is secreted inappropriately despite an elevation of
serum Ca
-Incidence: 20-40 ties, more common in women
-Etiology: parathyroid adenoma – 85%
hyperplasia – 15%
familial, part of MEN syndrome
Histopatologic types of PHPT
Sosa JA, Udelsman R Curr Probl Surg. 2003;40:812-849
85% 15% < 1%
adenoma hyperplasia carcinoma
Primary hyperparathyroidism
Symptoms:
Asymptomatic – majority patients
Fatigue, weakness, arthralgias, polyuria, constipation, nausea
CNS: lethargy, depression,. Confusion, stupor, coma
Kidney stones – calcium oxalate, calcium phosphate
CVS: arterial hypertension, short QT interval, bradycradia,
increased sensitivity to digitalis.
GIT: peptic ulcer disease, pancreatitis,
Bone disease
Primary hyperparathyroidism
Investigations
S-Ca elevated, S-P decreased, U-Ca increased, U-P increased
ALP normal/elevated
Dihydroxy vit D – elevated
PTH – elevated
X ray: osteitis fibrosa cystica, osteopenia, osteoporosis,
subperiostal bone resorption of the distal phalanges
DXA: disproportional loss of cortical bone
Primary hyperparathyroidism
Imaging methods:
US, CT, MIBI scintigraphy
Treatment:
Surgical removal of abnormal gland or glands.
Radioablation
Injection of etanol under US
Hypercalcemia of malignancy
Breast ca, lung, kidney
Hematologic malignancies, myeloma, T cell lymphomas
Mechanisms of hypercalcemia:
Localized bone destruction:
PTHrP – paraneoplastic production
Treatment of hypercalcemia
1. Hydration
2. Furosemide
3. Glucocorticoids – not effective in PHPT, sarcoidosis,
myeloma..
4. Calcitonin – inhibits osteoclastic resorption (s.c., i.m.)
5. Phosphate
6. Bisphosphonates – inhibit bone resorption
7. Acute severe hypercalcemia – hemodialysis
8. Calcimimetics - cinacalcet
Hypocalcemia
Abnormal reduction in serum ionized calcium concentration.
Etiology:
Hypoparathyroidism hungry bone syndrome
PTH resistance osteoblastic MT
Vitamin D deficiency acute pancreatitis
Vitamin D resistance
CHRF
Hypoparathyroidism
-surgical removal of PT during thyroidectomy
-Idiopathic- autoimmune ??
-Post neck iradiation
-PTH resistance - pseudohypoparathyroidism
Hypoparathyroidism
Symptoms:
often asymptomatic
Neuromuscular irritability: paresthesias, carpal pedal spasms
Laryngospasm, tetany
CNS: seizures, EEG, increased intracranial pressure
CV: prolonged QT, congestive heart failure
Other: abnormalities of teeth, skin, hair, cataract
Hypoparathyroidism
Chvostek sign: switching of the facial muscles following tapping
of the facial nerve
Laboratory manifestations:
Hypocalcemia, hyperphosphatemia
Low PTH levels
High PTH – pseudohypoparathyroidism
X ray: calcifications in basal ganglia
Hypoparathyroidism
Treatment:
Calcium
Vitamin D therapy
Acute: Calcium gluconicum i.v.
Chronic: Ca + vitamin D
