Group of rickets-like diseases
Classical nutritional rickets must be distinguished from hereditary disorders of phosphorus and calcium metabolism. The diagnostic workup must necessarily include the following nosologies:
- Vitamin D-resistant rickets (also known as phosphate diabetes) is a pathology accompanied by severe lower limb deformities.
- Vitamin D-dependent rickets.
- De Toni-Debré-Fanconi syndrome — a severe complex tubulopathy.
- Renal tubular acidosis.
- Hypophosphatasia — a hereditary bone tissue metabolism disorder.
A common and most striking clinical sign for all patients in this group is marked physical development retardation, primarily significant growth delay.
«Red flags» of hereditary osteomalacias
Specific markers help suspect a genetic nature of the disease instead of a usual nutritional deficiency. Red flags include:
- Resistance to ongoing treatment. The patient completely lacks the expected clinical response to the administration of standard doses of vitamin D.
- Atypical age and severity of manifestations. Development of severe grade III rickets or the appearance of pronounced lower limb deformities in children over 3 years of age.
- Combination with systemic manifestations. Bone changes do not occur in isolation, but are accompanied by growth retardation, renal involvement (polyuria appears), gastrointestinal disorders (persistent dyspepsia, vomiting), or neurological disorders (seizure syndrome).
- Burdened family history. Presence of similar renal pathologies or similar skeletal deformities in close relatives.
Basic screening and patient routing
If the pediatrician identifies well-founded suspicions of a genetically determined osteomalacia, the child must be referred to specialists: a geneticist, a nephrologist, and an orthopedist. Prior to these consultations, the attending physician must arrange a comprehensive basic screening.
Instrumental diagnostics:
- Radiography of the hands (to accurately determine bone age) and tubular bones of the legs (mandatory inclusion of knee joints).
- Densitometry to assess bone mineral density.
- Renal ultrasound to rule out nephrocalcinosis.
Laboratory blood diagnostics:
- Assessment of phosphorus and calcium metabolism parameters: levels of calcium, phosphorus, alkaline phosphatase (AP), and parathyroid hormone (PTH).
- Assessment of acid-base balance (ABB), including measurement of standard bicarbonate levels.
- Assessment of renal function by creatinine level.
Laboratory urine diagnostics:
- Determination of the phosphate/creatinine ratio.
- Assessment of bicarbonate, glucose, and amino acid excretion (critically important to rule out renal tubulopathies).
Management and therapy principles
Specific etiotropic therapy for the group of rickets-like diseases does not exist. Treatment tactics are always selected strictly individually depending on the verified nosology.
Medical correction may include active vitamin D metabolites, potassium compounds, inorganic phosphate preparations, as well as specialized agents for correcting acidosis (citrate mixtures, sodium bicarbonate solutions). In certain cases, specific drugs are prescribed (e.g., cysteamine bitartrate), and adequate rehydration is performed according to indications.
Global goals of pathogenetic therapy:
- Maximally possible slowing of disease progression.
- Minimization of severe orthopedic defects (in particular, leg deformities).
- Ensuring nephroprotection: prevention of nephrocalcinosis and chronic kidney disease (CKD), up to the prevention of end-stage renal disease.
Class and exam questions
Which specialists should a child be referred to when a rickets-like disease is suspected?
The patient must be routed to a geneticist, nephrologist, and orthopedist as soon as possible to clarify the diagnosis and adjust the tactics.
Which neurological and gastroenterological symptoms are not typical for ordinary rickets?
The presence of seizures, persistent vomiting, and marked dyspepsia refers to systemic manifestations requiring the exclusion of genetic osteomalacias.
Why is a renal ultrasound included in the screening?
Ultrasound is necessary to assess the condition of the kidneys, since many rickets-like diseases are accompanied by tubulopathies and a high risk of nephrocalcinosis.
What else to study on this topic
- Clinical presentation and diagnosis of phosphate diabetes
- De Toni-Debré-Fanconi syndrome: pathogenesis of complex tubulopathy
- Features of phosphorus-calcium metabolism in hypophosphatasia
- Principles of nephroprotection in rickets-like diseases
- Antenatal prevention of rickets and osteomalacias
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Other topics in "Chapter 3. Adaptation, Early Childhood Nutrition, Rickets"
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