Thyroid Pt 4 - Parathyroid Flashcards
Consist of 4 small glands located close to or within the back surface of the thyroid gland
- Cells secrete PTH
- Parathormone regulates calcium & phosphorus balance
- PTH regulates calcium & phosphorus metabolism by acting on bones, kidneys, & GI tract
- Bone is main storage site of calcium
- PTH increases bone resorption (bone release of calcium into the blood from bone storage sites), thus inc serum calcium
- In the kidneys, PTH activates vit D, which then inc the absorption of calcium & phosphorous from the intestines
- In the kidney tubules, PTH allows calcium to be reabsorbed & put back into the blood
Serum calcium lvls determine PTH secretion
Secretion dec when serum calcium lvls are high, & it incr when serum calcium lvls are low
PTH & calcitonin work together to maintain normal calcium lvls in blood & ECF
Calcium Homeostasis
The action of PTH is opposite to that of calcitonin, secreted by the thyroid gland, as calcitonin decreases serum calcium lvls
PTH also affects phosphorus lvls by
- Reduces the reabsorption of phosphate from the proximal tubules in the kidneys, leading to a dec in serum phosphorus lvls
- Inc bone resorption, leading to an inc in phosphorus release from the bone
- Inc SI absorption of phosphate
HYPERparathyroidism
___ PTH
___ Ca
___ Phos
↑
↑
↓
Sx’s
- apathy, fatigue
- muscle weakness, n/v, constipation, HTN, & cardiac dysrhythmias
R/t an inc’d Ca in the blood
- Pt may be irritable, have neurosis or psychosis (c/b the direct effect of Ca on brain & nervous system)
Causes
- Parathyroid tumor or cancer
- Congenital hyperplasia
- Neck trauma or radiation
- Vit D deficiency
- CKD w/hypocalcemia
- PTH-secreting ca’s of the lung, kidney, or GI tract
Assessments
- Mental status changes
- Strain urine (for renal calculi)
- Cardiovascular (typ QT shortening)
- GI
Treatments
If not a surgical candidate, then rx’s - cinacalcet [new rx’s called calcimimetics)
> If these don’t work, then oral phosphates; IV for when Ca drop needed fast. Calcitonin often combined w/glucocorticoids
Surgery
- When a parathyroidectomy is d/t hyperplasia, 3 plus half of 4th gland is removed. If all 4 removed, a small portion can be implanted in the forearm, where it produces PTH & maintains Ca homeostasis
Dialysis/diuretics
- furosemide & NS combined promote Ca excretion
- Fluids - aggressive hydration 2-3k mL as tol & a high fiber diet
- weigh daily
Clinical Manifestations of Hyperparathyroidism: “Bones, Stones, Moans, & Groans”
! Prevent injury
Outcome Management
Medical management
* Lower the elevated calcium lvls
* Anti-resorption agents (e.g., bisphosphonates)
Nursing management
* Impaired Urinary Elimination and Constipation
* Imbalanced Nutrition: Less Than Body Requirements
HYPOparathyroidism
___ PTH
___ Ca
___ Phos
↓
↓
↑
- Directly r/t ↓ PTH or ↓ effectiveness of PTH on target tissue
Either way, both result in LOW CALCIUM
Causes
- Rare, most commonly c/b removal of parathyroid during thyroid surgery or any type of head/neck trauma (iatrogenic)
- Spontaneous, unknown cause, possibly autoimmune (idiopathic)
- Hypomagnesemia may also cause hypoparathyoid
! Safety still an issue & pt @ risk for fx’s also
Assessments
- Muscle contractions
- Assess for tetany
> mild twitching → tetany → seizures - Chvostek/Trousseau’s signs
Sx’s
- hyper-excitation of muscles → diarrhea, hyperactive bowel sounds, cramping
- HR changes, dysrhythmias, typ QT elongation
- severe hypocalcemia causes hypotension
- loss of bone density leads to osteoporosis
Testing
- EEG
- Labs
- CT
Diet
- Inc Ca w/LOW phosphorus (NO milk, yogurt, or processed cheeses); take vit D to assist w/Ca absorption
Rx’s
- Give IV Ca, probably IV Ca gluconate
! institute seizure precautions; may also cause irritability to psychosis
Tetany - ___ Ca
↓ or ↑ ?
↓
Could be overt or latent
