Hypocalcemic vitamin D-dependent rickets

What it is

From: Orphanet

A rare, genetic disorder of vitamin D metabolism characterized by severe hypocalcemia leading to osteomalacia and rachitic bone deformations, and moderate hypophosphatemia.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Bone pain · Very frequent (99-80%)

An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) localized to bone.

Deformed rib cage · Very frequent (99-80%)

Malformation of the rib cage.

Elevated alkaline phosphatase of bone origin · Very frequent (99-80%)

An abnormally increased level of bone isoforms of alkaline phosphatase, tissue-nonspecific isozyme in the blood.

Elevated circulating parathyroid hormone level · Very frequent (99-80%)

An abnormal increased concentration of parathyroid hormone.

Enlargement of the costochondral junction · Very frequent (99-80%)

Abnormally increased size of the costochondral junctions, which are located between the distal part of the ribs and the costal cartilages, which are bars of hyaline cartilage that connect the ribs to the sternum.

Failure to thrive · Very frequent (99-80%)

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

Femoral bowing · Very frequent (99-80%)

Bowing (abnormal curvature) of the femur.

Flat occiput · Very frequent (99-80%)

Reduced convexity of the occiput (posterior part of skull).

Generalized aminoaciduria · Very frequent (99-80%)

An increased concentration of all types of amino acid in the urine.

Genu varum · Very frequent (99-80%)

A positional abnormality marked by outward bowing of the legs in which the knees stay wide apart when a person stands with the feet and ankles together.

Hypocalcemia · Obligate (100%)

The concentration of calcium in the blood circulation is below the lower limit of normal.

Hypophosphatemia · Very frequent (99-80%)

The concentration of phosphate ion in the blood circulation is below the lower limit of normal.

Increased susceptibility to fractures · Very frequent (99-80%)

An abnormally increased tendency to fractures of bones caused by an abnormal reduction in bone strength that is generally associated with an increased risk of fracture.

Low serum calcitriol · Obligate (100%)

The concentration of calcitriol in the blood circulation is below the lower limit of normal.

Other findings in the same source

From: Orphanet

Additional reported features include Motor delay (Very frequent (99-80%)); Muscle weakness (Very frequent (99-80%)); Osteomalacia (Very frequent (99-80%)); Postnatal growth retardation (Very frequent (99-80%)); Rachitic rosary (Very frequent (99-80%)); Rickets (Obligate (100%)); Secondary hyperparathyroidism (Very frequent (99-80%)); Subperiosteal bone resorption (Very frequent (99-80%)); Tetany (Very frequent (99-80%)); Thin bony cortex (Very frequent (99-80%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Infancy; Neonatal

Inheritance in the source

From: Orphanet

Autosomal recessive

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing Hypocalcemic vitamin D-dependent rickets is Orthopaedics, with a orthopaedic specialist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• What explains the change in pain, movement or function?
• Which activities need adjustment while the diagnosis is being clarified?
• What are the roles of rehabilitation, observation and surgery in this situation?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Hypocalcemic vitamin D-dependent rickets. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.