PARATHYROID FUNCTION TEST

Ms. Jean Dagondon, RMT

PARATHYROID GLAND

l Secretes parathyroid hormone (PTH) for calcium homeostasis

l Location of parathyroid gland

PARATHYROID HORMONE (PTH)

• Polypeptide composed of 84 amino acids

Pre-pro-parathyroid hormone è prohormone è active parathyroid hormone

• Composed of C-terminal ( amino acids 38-84) and N-terminal(1-34)

• Biochemical effects:

1. Bone – Calcium homeostasis

2. Kidney – inhibits reabsorption of PO4

- increase reabsorption of calcium and magnesium

3. Intestine – stimulate vitamin D to enhance calcium Reabsorption

• Assay:

RIA and IRMA- widely accepted methods

• ASSAY:

Immunoassays are available in the labs

• Reference ranges:

Ionized: 4.0-4.8 mg/dL 1.0-1.2mmol/L

2.0-2.4 mEq/L

Total: 9.2-11.0 mg/dL 2.30-2.74mmol/L

9.6-5.5 mEq/L

The Role of Calcium in the Human Body

• To provide the electrical energy for our nervous system

• To provide the electrical energy for our muscular system

• To provide strength to our skeletal system

üTHUS, calcium is the most closely regulated element in our bodies. Calcium is the only element/ mineral that has its own regulatory system (by the parathyroid glands)

The Role of Parathyroid Glands - To Regulate Calcium Levels

• The ONLY purpose of the parathyroid glands is to regulate the calcium level in our bodies within a very narrow range so that nervous and muscular systems can function properly. This is all they do.

• It works 24 hours a day and regulates via Negative Feedback (like a thermostat)

NORMAL PARATHYROID ACTIVITY

How does parathyroid hormone increases blood calcium levels?

þNORMAL SETTING:

PTH (parathyroid gland) 4 BONES 4 release calcium into the circulation (maintained by a feedback mechanism)

ýABNORMAL SETTING:

Too much production of PTH 4 parathyroid disease (hyperparathyroidism)

PARATHYROID QUICK FACTS:

• There are 4 parathyroid glands

• Located in the neck behind the thyroid

• Parathyroids are NOT related to the thyroid. Thyroid gland controls body metabolism, but parathyroid gland control body calcium. They have no relationship, they are just neighbors

• Parathyroid glands make a hormone – parathyroid hormone (PTH)

• Just like calcium, PTH has a normal range (we can see hoe good or bad a job the parathyroid glands are doing).

• All 4 parathyroids do exact the same thing

• Parathyroid glands control amount of calcium in your blood and in your bones

• You can easily live with one (or even ½) parathyroid gland
• Removing all 4 parathyroid glands will cause very bad symptoms-little calcium (hypoparathyroidism)
• When parathyroid glands go bad, it is just one gland that goes bad (96-98%) of the time--- it grows big (develops benign tumor) and produces too much hormone
• Parathyroid disease (hyperparathyroidism)---- osteoporosis
• There is only ONE way to treat parathyroid problems-- Surgery
• When the calcium in our blood goes too low, the parathyroid makes more PTH – causes body to put more calcium into the blood
• When the calcium in our blood goes too high, the parathyroid STOP making PTH--- they shut down
• Parathyroid disease (over-production of PTH) causes symptoms of the brain, muscles, and bones

HYPERPARATHYROIDISM

Ø Too much parathyroid activity due to a tumor:

>Parathyroid adenoma (1) – 97%

>Multiple adenomas-0.5%

>Parathyroid hyperplasia (4)-2.5%

>Cancer-less than 1%

Ø Women- 65%, men- 35%

Does Too Much Parathyroid Hormone and Calcium cause Symptoms?

• Hyperparathyroidism causes symptoms causes in almost everybody, but sometimes they are quite subtle

• It is never normal to have a high calcium level in your blood

• The one bad parathyroid gland is a tumor

Hoe does One Bad Parathyroid (the Adenoma) Affects the Other Three?

The normal organs will become dormant

-----After successful surgery----

Take lots of calcium

• Taking lots of calcium prevents a patient from getting sick (hypoparathyroidism) --- tingling in your hands and fingers and around your mouth, hands and feet. (Symptoms are temporary)

Symptoms of Parathyroid Disease

First identified in 1925, symptoms have become known as

“Moans, groans… with psychic overtones”

• Loss of energy. Don’t feel like doing much. Tired all the time

• Just don’t feel well; don’t quite feel normal. Hard to explain I just feel kind of bad

• Feel old. Don’t have the interest in things that you used to

• Can’t concentrate unlike before

• Depression

• Osteoporosis and osteopenia (bone density test)

• Bones hurt; typically bones in the arms and legs
• Spouse claims you are more irritable and harder to get along
• Gastric acid reflux
• Decrease in sex drive
• Thinning hair( older females
• Kidney stones
• High blood pressure (mild-severe)
• Heart palpitations

þIMPORTANT: Symptoms are NOT only seen in patients with really high calcium levels. In fact, the severity and type of symptoms patients get are NOT related to how high their calcium is.

The Minimally Invasive Radioguided Parathyroid (MIRP) Surgery

1. Make the over active parathyroid gland radioactive to be differentiated from all other structures in the neck

2. Operate only where necessary.

3. Use a miniature hand-held radiation detecting probe to find the radioactive parathyroid

4. Remove the radioactive tumor

5. Measure the radioactivity in the parathyroid to help make sure the patient is cure of the disease

6. Put bandage and get ready to go

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