Clinical forms and history taking
Physical examination and a detailed developmental history play the leading role in establishing the diagnosis. The clinical picture is largely determined by the course of the disease. In an acute course, processes of osteomalacia—softening of the bone tissue—dominate. This variant is most typical for infants in the first six months of life, although it can also be observed in older children during the height of the disease. In a subacute course, osteoid hyperplasia (excessive proliferation of unmineralized bone tissue) comes to the foreground, which usually becomes apparent by the end of the first year of life.
To confirm the diagnosis, it is necessary to analyze key anamnestic factors:
- Seasonality (time of year at the time of patient examination).
- Feeding pattern and dietary features.
- Presence of comorbid conditions.
- History of specific drug prophylaxis with vitamin D or lack thereof.
Radiological presentation
Instrumental methods are of an auxiliary nature. The most pronounced changes on radiographs of long bones are recorded during the height of the disease. The pathological process is localized predominantly in the epimetaphyseal zones.
Specific radiological signs of rickets include:
- Widening of the metaphysis and its "wine-glass" deformation (so-called cupping deformation).
- Pronounced blurring and indistinctness of provisional calcification zones.
- Indistinct contours of ossification centers.
- Appearance of a coarse trabecular pattern in the area of bone diaphysis.
Laboratory diagnostics and stages
The laboratory profile demonstrates the depth of phosphorus-calcium metabolism disorders and reflects the compensatory reaction of the parathyroid glands. The only reliable marker of the body's vitamin D sufficiency is the level of the 25(OH)D metabolite (calcidiol).
The severity of the process correlates with the following biochemical stages:
- Grade I severity. An initial decrease in 25(OH)D is noted. Compensatory mechanisms are activated: parathyroid hormone (PTH) and alkaline phosphatase (ALP) levels rise. At the same time, blood calcium and phosphorus remain normal or are slightly decreased.
- Grade II severity. The 25(OH)D level continues to drop. Compensation is gradually depleted: stable hypophosphatemia develops. Calcium remains at the lower limit of normal or begins to drop, while PTH and ALP continue to rise.
- Grade III severity. A profound 25(OH)D deficiency and a complete failure of compensation occur. A marked drop in both phosphorus and calcium (hypocalcemia) is observed. Secondary hyperparathyroidism develops with maximum values of PTH and ALP.
Interpretation of 25(OH)D levels
| Status | Level (ng/mL) | Level (nmol/L) |
|---|---|---|
| Adequate status | $\ge$ 20 | > 50 |
| Insufficiency | 12 – 20 | 30 – 50 |
| Deficiency | < 12 | < 30 |
| Risk of toxic effects | > 100 | > 250 |
Basic principles of therapy
Drug therapy must be accompanied by a complex of nonspecific measures. A key role is played by the normalization of the child's lifestyle, which includes:
- Adequate insolation (sufficient sun exposure).
- Organization of a full, balanced diet that strictly corresponds to the patient's age.
To memorize the dynamics of electrolytes by stage: vitamin D drops first (stage I), then phosphorus steadily decreases (stage II), and only when compensation fails does calcium collapse (stage III). The hormone PTH and the enzyme ALP increase at all stages.
Class and exam questions
What is the main criterion for diagnosing rickets?
The diagnosis is made primarily based on clinical manifestations and a thoroughly taken medical history. Laboratory and radiological methods are needed mainly for differential diagnosis.
Which blood parameter accurately reflects vitamin D deficiency?
The only reliable laboratory marker is the level of the 25(OH)D metabolite (calcidiol) in blood serum. Values below 20 ng/mL indicate insufficiency or deficiency.
How do bones change on radiographs during the height of the disease?
The pathological process is localized in the epimetaphyseal zones. The metaphyses widen and assume a cupping shape, while the mineralization zones and ossification centers become blurred and indistinct.
What else to study on this topic
- Mechanisms of development of osteomalacia and osteoid hyperplasia
- Differential diagnosis with rickets-like diseases
- Secondary hyperparathyroidism in the pathogenesis of rickets
- Specific drug prophylaxis with vitamin D
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Other topics in "Chapter 3. Adaptation, Early Childhood Nutrition, Rickets"
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