Biochemical diagnosis of osteoporosis. Markers of Osteoporosis - Causes, Symptoms and Treatment. MF.

Early biochemical diagnosis of osteoporosis.

The main goal of biochemical markers of osteoporosis is mainly that they can evaluate bone metabolism, which is very important for the choice of treatment and evaluation of treatment results, since patients with osteoporosis and high bone metabolism respond much more effectively to such active antiresorptive drugs,as estrogens and calcitonin. If the parameters of bone metabolism correspond to the lower third of the normal range or even lower, a significant therapeutic effect is unlikely.

Biochemical markers are also used to address the need for drug therapy in postmenopausal women: the higher the bone metabolism value and the lower the bone density compared to normal values, the greater the need for prescribing drug therapy. Determination of bone metabolism activity, can allow a doctor to adjust the prescribed therapy, until the final confirmation of the diagnosis by densitometric methods.

The results of very many clinical studies suggest that bone metabolism markers can be used to predict the effect of antiresorptive therapy on bone mass. Calculations reliably demonstrate that for the effectiveness of therapy in a single patient may need to be monitored for a long period( up to two years).The repeated determination of the level of bone markers makes it possible to shorten this period to three months.

Detection of markers of osteoporosis, unlike some instrumental methods of investigation, is not associated with irradiation of the body.

Determination of the level of biochemical markers of bone resorption and remodeling allows:

- In a preventive examination to identify patients with metabolic disturbances of remodeling and bone resorption;
- Evaluate and forecast the level of bone loss;
- Give an objective assessment of the effectiveness of the prescribed treatment within two months;
- Select the most effective drug in a particular case and determine the optimal dosage individually for each patient.

In biochemical diagnostics, the rate of formation and destruction of bone tissue is assessed. It is assumed that the prevalence of bone deterioration indicators over the indices of its formation indicates the development of osteoporosis or the insufficient effectiveness of its treatment.

Biochemical markers of bone remodeling

Alkaline phosphatase of bone origin is contained in the osteoblast membrane. As a remodeling index, the overall activity of alkaline phosphatase in serum is most often used, but this index is characterized by low sensitivity and specificity. Since the reasons for a significant increase in serum alkaline phosphatase levels may be different. For example, in elderly patients, this may be a consequence of a defect in the mineralization of bone tissue or the effect of one of many drugs that tend to increase the activity of the hepatic isoenzyme.

Osteocalcin, also called bone gla protein, is synthesized predominantly by osteoblasts and is incorporated into the extracellular matrix of bone tissue. Part of this protein penetrates into the bloodstream, where it can be measured by immune methods. The content of osteocalcin is determined in the blood, it is increased with the destruction of bone due to some endocrine diseases and is reduced with a lack of vitamin D.

It was found that in most conditions characterized by the conjugation of resorption and bone tissue synthesis, osteocalcin can be considered an adequate marker of bone remodeling speed, and in those situations where resorption and bone tissue synthesis are separated - a specific marker for bone formation.

Biochemical markers of bone resorption

Determination of fasting calcium in the morning portion of urine( correlated with creatinine excretion) is the cheapest method for evaluating bone resorption. This method is useful for determining significantly enhanced resorption, is insensitive.

Deoxypyridonolin( Dipid) is a cross-linked pyridine bond inherent in mature collagen and not subject to further metabolic changes. It is excreted in urine in free form( about 40%) and in peptide-related form( 60%).Definition of Dipida in urine has several advantages:

high specificity for the exchange of bone tissue;
absence of metabolic transformations before excretion in urine;
the ability to conduct research without prior dietary restrictions.

The importance of biochemical markers for the diagnosis and monitoring of osteoporosis therapy

The observations made on the treatment of the main types of drug groups led to the following conclusions:

- increased alkaline phosphatase and osteocalcin levels in serum are often observed in the treatment of patients with osteoporosis fluoride. The determination of these markers is recommended to control the stimulating effect of fluorides on bone formation;
- antiresorptive drugs such as estrogens and bisphosphonates, lead to a significant reduction in the concentration of resorption markers and bone tissue synthesis, down to the pre-menopausal level, with osteoporosis that developed after menopause.

Such dynamics of biochemical markers corresponded to a decrease in bone loss, established by osteodensitometry at 9 months.treatment.