The alleged hypoparathyroidism, or Albright's syndrome, is a group of genetically determined metabolic diseases in the course of which there is a deficiency of calcium in the body and related disorders. What are the causes and symptoms of pseudo-hypoparathyroidism (Albright's syndrome)? What is the treatment of this disease?

Alleged hypoparathyroidism( pseudohypoparathyroidism ), i.e.Albright syndrome , is a group of genetically determined metabolic diseases, the essence of which is the resistance of bones and kidneys to the action of parathyroid hormone (PTH) - a hormone produced by the parathyroid glands. As a consequence, there is a shortage of calcium in the body and related disorders.

Albright syndrome is not to be confused with McCune-Albright syndrome which is a completely different disease.

What is PTH and how does it work?

Parathyroid hormone( PTH ) is a hormone produced by the parathyroid glands that regulates the levels of calcium, phosphate, and vitamin D in the blood. Its secretion by the parathyroid glands depends on two factors: the level of calcium and the active form of vitamin D3 in the blood. If the level of calcium in the blood is too low, the parathyroid glands are stimulated to release PTH in order to restore the normal levels of this element in the body. Conversely, high levels of calcium inhibit the production of this hormone. It is similar with vitamin D3 - a decrease in its blood level stimulates the secretion of PTH by the parathyroid glands, and its growth is inhibited.

Parathyroid hormone, when released into the blood by the parathyroid glands, binds to a receptor located on the cells of target organs, i.e. bones and kidneys. As a consequence, the enzyme adenylate cyclase is activated, which begins to produce the mediator of parathyroid hormone activity - cAMP (cyclic adenosine monophosphate). It is through this mediator that parathyroid hormone can increase the concentration of calcium in the blood, which, under the influence of parathyroid hormone, penetrates from the bones. In addition, parathyroid hormone removes excess phosphate from the body by increasing its excretion in the urine.

Pseudo-hypoparathyroidism (Albright's syndrome) - causes

The cause of the disease is a mutation of the parathyroid hormone receptor gene, which contributes to the damage of this receptor and, consequently, to its dysfunction. In conjunction withTherefore, although the parathyroid glands are functioning properly and produce adequate amounts of parathyroid hormone, this hormone is unable to act on target organs. As a consequence, it is allegedly deficient, followed by a decrease in blood calcium levels and an increase in phosphate levels and the associated effects. It should be noted that the concentration of calcium and phosphate is interdependent. If the calcium level drops, the phosphate level increases.

Albright's syndrome is an autosomal dominant disorder, which means that it is enough to inherit just one defective gene to develop the disease.

Types of alleged hypoparathyroidism and their characteristics

  • Type Ia - tissue resistance is observed not only to PTH, but also to TSH receptors, glucagon and gonadotropins. As a result, there are many abnormalities in the form of changes in the skeletal system and mental retardation. Moreover, genetic disorders translate into changes in the concentration of certain ions. Patients are dominated by a decreased level of calcium in the blood serum, referred to in medical terminology as hypocalcemia (each prefix, hypo-, means a reduced amount of a certain substance). Additionally, there is an excess of phosphate - hyperphosphatemia (the prefix hyper means something that is in excess). Due to the described tissue resistance to parathyroid hormone, and this causes the accumulation of this compound in the body. Serum hyperphosphatemia, on the other hand, is reflected in the general urine test, where reduced phosphate secretion takes place.
  • Type Ib - it is a form of alleged hypoparathyroidism, in which the course, similarly to type Ia, is characterized by hypocalcemia, hyperphosphatemia, excessively high concentration of parathyroid hormone, but reduced secretion of phosphate in the urine. Regarding the form Ia, there is no insensitivity of the target tissues to other substances - TSH, glucagon or gonadotropins.
  • Type Ic - morphologically and clinically it is a mirror image of Ia, but the etiology of the disorder is not fully specified.
  • Type II - characterized by a correct response of the receptors for TSH, glucagon and gonadotropins, no disorders in the skeletal system, but a disturbance in the secretion of phosphates after the administration of parathyroid hormone. The cause is attributed to low vitamin D levels. Moreover, in patients with this type of Albright syndrome, the coexistence of myotonic dystrophy, ie a genetic disease with atrophy of muscle structures, is observed. The key factor is the origin of the abnormal gene, in the case of paternal inheritance it is not manifested by hormonal disorders, but when the genecomes from the mother, the patient presents symptoms of the disease.

Pseudo-hypoparathyroidism (Albright's syndrome) - symptoms

Symptoms of Albright's syndrome are:

  • characteristic appearance: obesity, short stature, short neck, round face;
  • changes in the skeletal system: demineralisation of bone tissue (rickets, bone softening), shortening of the fingers in the distal part and metacarpal bones, shortening of the metatarsal fingers, phalanges and metacarpal bones, subcutaneous calcification and ossification, "obstetrician's hand" (characteristic tightening palm);
  • endocrine gland secretion disorders - most often hypothyroidism, adrenal gland hyperfunction;
  • disorders of the neuromuscular system: neuromuscular hyperactivity, cramps and leg cramps, eyelid muscle spasms, laryngospasms, seizures;
  • delay in development and puberty, decreased libido (due to ovarian failure in women and testes in men);

Possible hypoparathyroidism (Albright's syndrome) - diagnosis

Albright syndrome leads tohypocalcaemia , i.e. a decrease in blood calcium (less than 2.25 mmol / l) andhypophosphatemia - increases in blood phosphate levels (over 1.4 mmol / l). Therefore, in the first place, laboratory tests are performed to determine the concentration of these substances in the blood.

In addition, set the level:

  • estradiol in girls,
  • testosterone in boys,
  • FSH level (follicle stimulating hormone which stimulates Graafian follicle maturation and estrogen production),
  • LH (lutropin - a hormone that stimulates the synthesis of testosterone by Leydig cells in men, and increases the production of progesterone in women).

Pseudo-hypoparathyroidism (Albright's syndrome) - treatment

The goal of treating pseudo-hypoparathyroidism is to normalize the levels of calcium and phosphate. The therapy consists in combating hypocalcemia with calcium and vitamin D3 supplementation, as well as in the treatment of magnesium and phosphate disorders. The treatment is complemented by a low-phosphate diet.

Category:

Genetic diseases