Download PARATHYROID GLAND PATHOPHYSIOLOGY

PARATHYROID GLAND
PATHOPHYSIOLOGY
Yousaf khan
Lecturer Renal Dialysis Technology
PARATHYROID GLANDS
The parathyroid gland is located in the
neck
 Four glands located on the posterior
surface of the thyroid gland
 Derived from the 3rd and 4th pharangeal
pouches
 The parathyroid produces a hormone
called PTH.

Location of Parathyroid Glands
The Basics

Parathyroid hormones is the most
important Endocrine regulator of calcium
and phosphorus concentration in extra
cellular fluid.
How does the hormones produced
maintain homeostasis?
Like all endocrine glands, parathyroid’s
makes a hormone, parathyroid hormone
(PTH) has a very powerful influence on the
cells of the bones which causes them to
release their calcium into the blood stream.
Function of Parathyroid Hormone
Parathyroid hormone regulates calcium,
phosphorous, magnesium balance within
the blood and bone by maintaining a
balance between the mineral levels in the
blood and the bone.
TARGET ORGANS FOR PTH
G.I.T
 Bone
 Kidney
 Lactating Mammary Glands

Action on GIT
PTH increase Ca++ absorption from
intestinal mucosa
 Increase formation of 1, 25dihydroxycholecalciferol from Vitamin D3,
which increase absorption by:
 Increase formation of calcium binding
protein
 Increase formation of calcium stimulant
ATPase
 Increase formation of alkaline phosphatase, it
also increase phosphorus absorption from
GIT.

Action of Bone
Increase absorption of Calcium from
bone into the blood in the following ways.
 Activation of all osteoclasts
 Rapid formation of osteoclasts from
mesenchymal stem cells
 Delay in conversion of osteocytes into
osteoblasts.

Action on Kidneys




Increase renal tubular reabsorption of
calcium
Increase reabsorption of Mg and H
Decreased phosphate, sodium and
bicarbonate reabsorption from the proximal
tubule
Increased proximal tubule 1-alphahydroxalase activity
Action on lactating mammary glands

Reduces excretion of calcium in milk
Control of PTH secretion

a.
b.
c.
PTH is not control by Pituitary Gland or
any other nervous factor, but controlled
by blood calcium level.
Low calcium level of blood increases
PTH secretion
High plasma phosphate level promotes
PTH secretion
Rise in plasma Mg level lowers PTH
secretion
CALCITONIN


Polypeptide hormone
Synthesized and secreted by the
parafollicular C-cells of the thyroid gland
ACTIONS OF CALCITONIN ON
BONE
Decresaed osteoclastic number
 Decreased osteoclastic activity
 Actions are proportional to baseline rate of
bone turnover
Hypoparathyroidism

Parathyroid gland secretes decrease amount of
PTH.

Causes:
Surgical ( thyroidectomy)
Anatomical ( Malformation )
Digeorge syndrom ( failure in the development
of the third and forth branchial pouches)
Idiopathic
Infection
necrosis
a.
b.
c.
d.
e.
f.
Signs and symptoms
Hypocalcemia: low level of calcium in
blood but increase blood phosphrous
level.
 Increase excitability of CNS and
peripheral nerves. These effects and
hypocalcemia lead to Tetnay.
 Tetnay: a condition of intermittent
muscular spasms, caused by parathyroid
malfunction and consequent calcium
deficency.

Hyperparathyroidism
PTH secrete increase amount of
Parathyroid hormone.
 Charachterized by hypercalcemia, it may
three type
 Primary type
 Secondary type
 Tertiary type

Causes:
a. Hyperplasia of all PT gland
b. Localized tumor
SIGNS AND SYMPTOMS
Demineralization of bones
 Deformation of bone
 Muscular weakness
 Constipation
 Abdominal pain
 Peptic ulcer
 Nausea
 Vomiting
 Joint pains and arthritis

Thank you