Clase sencilla de la fisiología y patologia del hiperparatiroidismo Para consulta rapida

1. Hiperparatiroidismo y trastornos
del calcio
Hospital General Dr. Nicolás San Juan
ISEM
Servicio de Medicina Interna
Dr. Daniel Rebolledo García
Noviembre, 2019

2. • A 62-year-old woman is found on routine laboratory testing to have a serum
calcium level of 10.8 mg per deciliter (2.7 mmol per liter) (normal range, 8.4 to
10.4 [2.1 to 2.7]). The serum intact parathyroid hormone (PTH) concentration
is 70 pg per milliliter (normal range, 15 to 75).
• Her history is notable only for hypertension that is well controlled with an
angiotensin-receptor blocker; there is no history of kidney stones or fractures.
Her family history is negative for hypercalcemia or endocrine tumors. Her 24-
hour urinary calcium and creatinine levels are 280 mg and 1050 mg,
respectively, and the ratio of calcium to creatinine clearance is 0.025.
• Bone densitometry shows T scores at the lumbar spine of −1.8, at the total hip
of −2.2, and at the distal third of the radius of −3.0. How should she be further
evaluated and treated?

3. Definición
• Hiperfuncionamiento de las glándulas paratiroides.
• Homeostasis del calcio.
• PTH y péptido simil a la PTH.
• Calcitonina.
• Vitamina D.

9. • Primary hyperparathyroidism is the most common cause of hypercalcemia
and should be considered in any person with an elevated serum calcium
level.
• With increased detection by means of routine calcium screening, the
clinical profile of primary hyperparathyroidism in Western countries has
shifted from a symptomatic disease, characterized by hypercalcemic
symptoms, nephrolithiasis, overt bone disease, and neuromuscular
symptoms to one with subtle or no specific symptoms (“asymptomatic”
primary hyperparathyroidism).
• In the developing world, the symptomatic variant still dominates

10. • PHPT is a common endocrine disorder that is characterized by
hypercalcaemia and elevated or inappropriately normal levels of PTH.
• PHPT results from excessive secretion of PTH from one or more of the
parathyroid glands.
• PHPT is caused by a solitary parathyroid adenoma in 80% of cases,
whereas four-gland hyperplasia accounts for 10–15%, multiple adenomas
for 5% and parathyroid cancer for <1% of cases.

11. • The incidence of primary hyperparathyroidism peaks in the seventh decade.
• Most cases occur in women (74%), but the incidence is similar in men and women
before 45 years of age.
• Incidence estimates for PHPT vary from ~0.4 to 82 cases per 100,000.
• The incidence of PHPT increases with age and is higher in women and African
Americans than in men and other racial groups, respectively.

12. • Half of all patients with PHPT are postmenopausal women, although the disorder
can occur at any age.
• Etiology:
• Idiopathic
• Thiazides use
• Ionizing radiation, especially in childhood
• Chronic lithium use, which decreases the sensitivity of the parathyroid glands to calcium.

15. • Classic symptoms and signs of primary hyperparathyroidism are rare today, but
nephrolithiasis still occurs in 4 to 15% of cases.
• Patients may have weakness, easy fatigability, anxiety, and cognitive impairment even when
the level of serum calcium is modestly increased.
• Associated insulin resistance, hyperglycemia, and dyslipidemia (decreased levels of high-
density lipoprotein cholesterol and increased levels of total triglycerides) have been reported,
but it remains unclear.
• Hypertension is also common and, with sophisticated testing (which is not routinely
performed), subtle cardiovascular changes (i.e., increased vascular stiffness and endothelial
dysfunction) may be detected.
• Low bone mineral density, particularly at sites enriched in cortical bone (e.g., the distal third
of the radius) is common.
Symptomatic hypercalcemia

16. Asymptomatic hypercalcaemia
• Most patients in the developed world are now diagnosed on routine screening
at an asymptomatic stage or during assessment for low bone mineral density.
These patients may present with non-specific symptoms of mild
hypercalcaemia, such as fatigue, mild depression or malaise.

17. Normocalcaemic hyperparathyroidism
• Patients who present with an incidental finding of raised PTH and normal serum calcium
are classified as having normocalcaemic hyperparathyroidism. These patients may present
for evaluation of osteoporosis or a fragility fracture and raised PTH is identified on further
assessment of the osteoporosis.
• The natural course of normocalcaemic hyperparathyroidism has not been wellstudied, but
prospective observational data suggest that some patients progress to hypercalcaemic
hyperparathyroidism.
• Before confirming this diagnosis, it is essential to exclude vitamin D inadequacy and renal
impairment because these conditions may present with increased PTH values and normal
serum calcium.