parathyroids
TRANSCRIPT
PARATHYROIDSPARATHYROIDS
Anatomy
PhysiologyPhysiology
Secretes parathyroid hormone (PTH)
PTH produced by the chief cells PTH secretion is controlled by a complex
feed back mechanism dependent on serum Ca levels
PTH or its fragments can be measured by radio immunoassay
Actions of PTHActions of PTH
Stimulation of osteoclastic activity bone resorption and mobilization of Ca &Phosphate
Absorption Ca from the gut Reduces the urinary Ca by increasing
the reabsorption Ca by renal tubules Reduces the renal tubular absorption of
PO4 Phosphaturia
CalcitoninCalcitonin
Secreted by C cells of thyroidOpposite action of PTH Serum CaCa storage in the bones
HYPERPARATHYROIDISMHYPERPARATHYROIDISM
Secretion of PTHOne of the most common causes of
hypercalcaemiaLarge no. of patients are asymptomaticIn India a high proportion of patients
presents with skeletal and renal disease
ClassificationClassification
Primary Hyperparathyroidism(PHPT) – inappropriately secretion of PTH
Secondary hyper parathyroidism – chronic hypocalcaemia reactive hyperplasia of all four glands
Tertiary hyper parathyroidism – reactive hyperplasia, the glands become autonomous e.g, chronic renal failure pt. After transplantation
PathologyPathology
Parathyroid adenomaUsually single,5% multipleWhole gland is enlarged, darker in color
more vascular than usualA rim of compressed normal tissues seen
surrounding the adenomaPredominance of chief or clear cells
Pathology(contd.)Pathology(contd.)
Parathyroid hyperplasia – hyperplasia of all the glands
Parathyroid carcinoma – rare (<1%) – palpable swelling , very large swelling infiltrating to the thyroid or adjacent structures – distant metastasis & recurrence have been reported
Multiple Endocrine Multiple Endocrine Neoplasia (MEN) SyndromeNeoplasia (MEN) Syndrome
Autosomal dominant disorderAPUD cells are involvedMEN Type I (Werner syndrome)
Hyperparathyroidism,pancreatic islet cell tumors,pituitary tumor
MEN Type IIMEN Type II
MEN Type IIA(Sipple syndrome)
MedullaryCa.thyroid,Phaeochromacytoma,Hyperparathyroidism
MEN TypeIIB(MEN TypeIII)
Medullary Ca ,Phaechromocytoma ,and mucosal neuromas
Clinical presentation Clinical presentation (contd.)(contd.)
Skeletal - mild to crippling bone disease
Osteitis fibrosa cystica, Brown tumors , single or multiple bone cysts, pseudomotor & pathological fractures . Vague pain in the bone and joints
Renal stones, nephrocalcinosis
Clinical PresentationClinical Presentation
Age 20 – 45Females :Males = 2:1Most common presentation in the
western world Asymptomatic hypercalcemia
Classical manifestations in the 3rd world ,viz. “Bones,stones,abdominal groans & psychic moans”
Clinical presentation Clinical presentation (contd.)(contd.)
Gastro intestinal - nausea, vomiting,anorexia and weight loss, peptic ulceration, pancreatitis.
Nervous system – lethargy, listlessness,personality changes,irrational behavour and memory loss. Hyper calcemia depression of nervous system coma
Laboratory findingsLaboratory findings
Serum Ca - most common finding PHPT. Normocalcemic PHPT not uncommon in India. Serum Ca level to be corrected with respect to serum albumin
Urinary Ca –24 hrs Serum alk. Phosphatase in bone diseaseSerum PTH – Normal – 65 pg/ml
Clinical presentation Clinical presentation (contd.)(contd.)
Other complications: Corneal calcification ,Itching
Hypertension is seen in many pts. Reason not clear
Common causes of Common causes of hypercalcemiahypercalcemia
a.Bony metastasis – breast, bronchus, prostate,kidney, thyroid
b.PTH secreting solid tumorsc.Haematological malignancies –multiple
myelomad.Vit D intoxicatione.Sarcoidosisf.Immobilisation,medications like lithium,
thiazide etc
Imaging investigationsImaging investigations
Radiology Useful for skeletal lesionsUltrasound Adenoma or multiple
enlarged glands may be detectedCT Scan Lesions in the chestThallium Technetium subtraction scan99 Tc Sestambi scanSelective angiography & venous sampling
TreatmentTreatment
Surgery is the treatment of choice
Parathyroid adenoma Excision of the adenoma
Parathyroid hyperplasia If more than one gland is involved,3 ½ gland can be removed or total parathyroidectomy with auto transplantation
Parathyroid Ca Hemithyroidectomy + involved gland