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# Rickets and osteomalacia

Bone fails to mineralise for lack of vitamin D, calcium or phosphate: in children it bends (rickets), in adults it softens and hurts (osteomalacia).

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Femur](https://durgical.com/en/anatomy/femur/)
- [Tibia](https://durgical.com/en/anatomy/tibia/)
- [Fibula](https://durgical.com/en/anatomy/fibula/)
- [Skin](https://durgical.com/en/anatomy/skin/)

## In biochemistry

- [Alkaline phosphatase (ALP) as a lab test](https://durgical.com/en/biochemistry/topics/alkaline-phosphatase-as-a-lab-test/)
- [Nuclear receptors](https://durgical.com/en/biochemistry/topics/nuclear-receptors/)
- [Vitamin D (calcitriol)](https://durgical.com/en/biochemistry/molecules/vitamin-d/)
- [Calcium and phosphate](https://durgical.com/en/biochemistry/topics/calcium-and-phosphate/)

## In histology

- [Ossification, growth plate and bone remodeling](https://durgical.com/en/histology/ossification-growth-plate-and-bone-remodeling/)

## In physiology

- [Calcium regulation: PTH, vitamin D and calcitonin](https://durgical.com/en/physiology/calcium-regulation-pth-vitamin-d-and-calcitonin/)
- [Bone remodeling](https://durgical.com/en/physiology/bone-remodeling/)
- [Phosphate and FGF-23](https://durgical.com/en/physiology/phosphate-and-fgf-23/)
- [Absorption of iron, calcium and vitamin B12](https://durgical.com/en/physiology/absorption-of-iron-calcium-and-vitamin-b12/)
- [Vitamins and minerals: a physiological overview](https://durgical.com/en/physiology/vitamins-and-minerals-a-physiological-overview/)

## Why it happens

- [Vitamin deficiencies: what each one does to tissue](https://durgical.com/en/general-pathology/vitamin-deficiencies-what-each-one-does-to-tissue/)

## What it is

Defective mineralisation of bone matrix (osteoid). In children, with open growth plates, it is called rickets; in adults, osteomalacia.

## Who gets it

It has returned in exclusively breastfed infants without supplements, with dark [skin](https://durgical.com/en/anatomy/skin/) or little sun, and in institutionalised older adults. In tropical areas such as Colombia it is less common thanks to sunlight, but it is seen with malnutrition, malabsorption and [kidney](https://durgical.com/en/anatomy/kidney/) disease.

## Causes

- Vitamin D deficiency: little sunlight, poor diet, malabsorption, [liver](https://durgical.com/en/anatomy/liver/) disease
- Chronic kidney disease (no 1α-hydroxylation)
- Very low calcium diet
- Renal phosphate wasting: X-linked hypophosphataemia (high FGF23), Fanconi syndrome
- Vitamin D-dependent rickets type 1 (CYP27B1) and type 2 (VDR receptor)
- Drugs: anticonvulsants, antiretrovirals such as tenofovir

## Risk factors

- Prolonged exclusive breastfeeding without vitamin D supplements
- Dark skin, full-body clothing, staying indoors
- Prematurity
- Bariatric surgery, coeliac disease

## Pathophysiology

Without calcitriol little calcium is absorbed; PTH rises to hold calcium and wastes phosphate in urine. The calcium × phosphate product stays low and osteoid does not mineralise. In the growth plate hypertrophic chondrocytes pile up uncalcified: metaphyses widen and cup and bones bend under weight. In adults soft osteoid builds up: bone pain, muscle weakness and pseudofractures.

## Classification

- Calcipenic: insufficient vitamin D or calcium (high PTH)
- Phosphopenic: renal phosphate wasting (normal PTH, high FGF23 in the X-linked form)
- Vitamin D-dependent rickets types 1 and 2

## Symptoms and signs

- Children: bowed legs (genu varum) or knock knees, late walking, late fontanelle closure
- Rachitic rosary (swollen costochondral junctions), widened wrists and ankles
- Craniotabes, frontal bossing, late tooth eruption and caries
- Adults: diffuse bone pain, proximal muscle weakness, waddling gait
- Fractures with minor trauma

## Red flags

- Hypocalcaemia with tetany or seizures in infants
- Hypocalcaemic cardiomyopathy
- Breathing difficulty from a soft [chest](https://durgical.com/en/anatomy/region/chest/) wall

## Diagnosis

**Clinical**
Typical deformities and risk factors in a child; bone pain, proximal weakness and fragility fractures in an adult.

**Tests**
High alkaline phosphatase, low phosphate, low or normal calcium, high PTH, low 25-OH-D in nutritional forms; urine phosphate and FGF23 in phosphopenic forms.

**Imaging**
Wrist or knee X-ray: widened, cupped, frayed metaphyses. In adults, Looser zones (pseudofractures) in the femoral neck, pubis and [ribs](https://durgical.com/en/anatomy/ribs/); low bone density.

## Treatment

**Medical**
Replace vitamin D and ensure enough dietary or supplemental calcium

**Medical**
In renal or genetic causes: calcitriol or active analogues, phosphate or specific treatment

**Follow-up**
Follow calcium, phosphate, alkaline phosphatase, PTH and X-rays until healing

**Surgical**
Corrective osteotomy for severe persistent deformities

**Lifestyle**
Sensible sun exposure and vitamin D-containing foods

## Complications

- Permanent bone deformity and short stature
- Narrow [pelvis](https://durgical.com/en/anatomy/region/pelvis/) that complicates childbirth
- Fractures
- Hypocalcaemic seizures

## Prognosis

The nutritional form heals within weeks to months with treatment and many mild deformities correct with growth; genetic forms need lifelong treatment.

## Prevention

- Vitamin D supplements for breastfed infants as guidelines advise
- Reasonable sun exposure, fortified foods
- Monitoring people with malabsorption or on anticonvulsants

## Test yourself

Think of the answer, then tap the question to see it.

## Why does vitamin D deficiency lower serum phosphate?

Low calcium raises PTH, which increases renal phosphate excretion.

## What is the rachitic rosary?

Palpable swellings at the costochondral junctions from accumulated unmineralised cartilage and osteoid.

## What are Looser zones?

Pseudofractures: radiolucent bands perpendicular to the cortex, typical of osteomalacia.

## What separates phosphopenic from calcipenic rickets?

In phosphopenic rickets PTH and calcium are normal and the kidney wastes phosphate (for example, high FGF23 in the X-linked form).

## What is the most sensitive biochemical marker of active rickets?

Raised alkaline phosphatase, reflecting increased osteoblast activity.

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## Related conditions

- [Osteoporosis](https://durgical.com/en/conditions/osteoporosis/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Primary hyperparathyroidism](https://durgical.com/en/conditions/primary-hyperparathyroidism/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Rickets: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000344.htm) (MedlinePlus, US National Library of Medicine, 2026); [Osteomalacia: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000376.htm) (MedlinePlus, US National Library of Medicine, 2026); [Vitamin D Deficiency: MedlinePlus](https://medlineplus.gov/vitaminddeficiency.html) (MedlinePlus, US National Library of Medicine, 2026); [Vitamin D-dependent rickets: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/vitamin-d-dependent-rickets/) (MedlinePlus, US National Library of Medicine, 2026); [Vitamin D Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/vitamin-d-test/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Source: https://durgical.com/en/conditions/rickets-and-osteomalacia/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/rickets-and-osteomalacia/