Last updated:
April 1, 2026
Table Of Contents
Rickets
Rickets is a serious condition that is due to impaired bone mineralization before epiphyseal closure. It is caused by a deficiency in vitamin D, calcium, or phosphorus, and mainly manifests as skeletal malformations.
It peaks between 6 and 15 years, and affects boys and girls equally.
Classification of Rickets
| Classifcation | Examples |
|---|---|
| Vitamin D-related rickets | Vitamin D deficiency rickets, vitamin D-dependent rickets (type 1 and type 2) |
| Hypocalcemia-related rickets (calcipenic rickets) | Renal osteomalacia, hypocalcaemia (calcipenic) rickets |
| Hypophosphatemia-related rickets (phosphopenic rickets) | X-linked hypophosphatemic rickets (XLHR), autosomal dominant hereditary rickets (ADHR), autosomal recessive hereditary rickets (ARHR), hereditary hypophosphatemic rickets with hypercalciuria (HHRH), High FGF-23 (phosphantoins), Fanconi syndrome, Dent’s disease |
Risk factors for rickets
| Risk factor | Description |
|---|---|
| Gender | More common in males. There might be a protective locus on the X chromosome |
| Age | Infants are susceptible from 3 – 4 months of age and peak at 18 months |
| Rapid growth | Prematurity, twins |
| Protracted exclusive breastfeeding | The vitamin D content of breast milk is low (15–50 IU/L). Exclusively breastfed infants consuming an average of 750 mL of breast milk daily ingest only 10–40 IU/day of vitamin D. |
| Rachitogenic diet | Cereals and excessive leafy vegetables contain excess phytate and oxalates that form insoluble calcium complexes. Unfortified animal milk and food rich in carbohydrates are also vitamin D-deficient and can lead to rickets |
| Lack of exposure or access to UV rays | This can be caused by excessive infant wrapping, darker skin, high atmospheric pollution, and living in high-rise apartments. Most breastfed infants need to be exposed to sunlight for at least 30 minutes/ week while wearing only a diaper in order to maintain 25(OH)D levels at >20 ng/mL. |
Head and Neck Skeletal Manifestations
| Manifestation | Description |
|---|---|
| Craniotabes | Softening of the skull bones, which yield under pressure like a ping-pong ball (due to thinning of the inner table of the skull). It can be detected by pressing over the occipital or parietal bones (along the sutures). This disappears by the end of 1st year. Differentials include prematurity, osteogenesis imperfecta, hydrocephalus, congenital syphilis, hypervitaminosis A, marasmus, and thalassemia |
| Large head | Especially marked if rickets develops in the 1st year of life |
| Caput quadratum | Asymmetrical and/or box-shaped head |
| Delayed closure of fontanelles | Wide, open anterior fontanelle or open posterior fontanelle. Differentials include prematurity, osteogenesis imperfecta, hydrocephalus, congenital syphilis, hypervitaminosis A, marasmus and thalassemia |
| Bossing of the frontal and parietal bones | Due to excess osteoid deposition |
| Delayed teething | Due to deficient enamel. May be associated with dental hypoplasia and caries of existing teeth |
Chest, Vertebral and Pelvic Manifestations
| Manifestation | Description |
|---|---|
| Rachitic rosary | Rounded, regular, and non-tender palpable and/or visible bead-like enlargement of the costochondral junction due to excess osteoid deposition. Differentials include scurvy (scorbutic rosary – angular, irregular and non-tender and associated with a depressed sternum), hypophosphatemia, chondrodystrophies and healing fractures |
| Harrison sulcus | Transverse groove along the costal insertion of the diaphragm due to muscles pulling on the soft ribs. |
| Pectus carinatum (pigeon chest) | The sternum and adjacent cartilage project outwards |
| Pectus excavatum (funnel chest) | Depression of the sternum and flaring of the lower ribs |
| Vertebral column abnormalities | Kyphosis, scoliosis and lumbar lordosis |
| Contracted inlet | Forward projection of the sacral promontory. May lead to obstructed labour later in life |
| Contracted outlet | Forward projection of the coccyx. May lead to obstructed labour later in life |
Extremity Manifestations
| Manifestation | Description |
|---|---|
| Widened wrist and ankles | Due to the broadening of the epiphysis of long bones |
| Marfan sign of the ankle | Palpable transverse groove over the medial malleolus (double medial malleolus) due to unequal growth of the two ossification centres |
| Bowing of forearms | In crawling infants, due to weight-bearing on soft bones |
| Genu varum (bow legs) | More common in younger children |
| Genu valgus (knock knees) | More common in older children |
| Genu recurvatum | Knee hyperextension |
| Greenstick fractures | There is increase tendency of bone fractures |
| Waddling or antalgic gait |
- Pathophysiology
- Hypocalcemia and severe hypophosphatemia → prevention of hydroxyapatite crystals from forming properly within the collagenous matrix of bone → soft and pliable bones that are prone to deformities
- Hypophosphatemia → inhibition of apoptosis of hypertrophic chondrocytes → excessive osteoid and accumulation of chondrocytes → widening and disorganization of the growth plates
- Non-skeletal signs and symptoms
- Anorexia
- Irritability
- Bone pain
- Paraesthesias
- Profound sweating
- Especially of the forehead
- May be caused by bone pain
- Hypocalcemic seizures
- Especially in the first year of life
- Delayed motor milestones, e.g., neck support, sitting without support, and walking
- Visceroptosis of the liver and spleen
- Abdominal distension +/- umbilical hernia. Due to:
- Hypotonia of the abdominal muscle secondary to hypophosphatemia
- Visceroptosis
- Weakened ribs
- Increased susceptibility to infectious diseases
- Constipation
- Due to intestinal hypotonia
- Differentials
- Osteomalacia
- Familial hypophosphatemia (X-linked hypophosphataemic rickets)
- Hypophosphatasia
- Investigations
- Basic Metabolic Panel: including serum calcium, Phosphate, and Magnesium levels
- Urine electrolytes for calcium and phosphate
- 25-OH-Vitamin D and Calcitriol levels
- Parathyroid hormone levels
- Complete blood count
- AP and Lateral X-ray of the knee, wrist or ankle: radiographic findings of deficient mineralization are evident at metaphyseal zones of provisional calcification, where there is excess non-mineralized osteoid
- Metaphyseal Cupping (concavity of metaphysis)
- Fraying (indistinct margins of the metaphysis)
- Splaying (widening of metaphyseal ends)
- Looser’s zone (pseudofracture on the compression side of the bone)
- Treatment
- Dietary advice to ensure adequate intake of vitamin D and calcium
- Encourage safe sunlight exposure
- Replacement therapy
- Ergocalciferol or cholecalciferol for vitamin D replacement
- Calcium lactate or calcium carbonate to correct hypocalcemia
- Phosphate binders, low phosphate diet, and calcitriol replacement for renal osteomalacia
- Phosphate supplements and calcitriol for resistance cases or X-linked hypophosphatemic rickets
- Treat the underlying cause, e.g., malabsorption syndrome or renal tubular acidosis
- Monitor serum calcium, phosphate, and alkaline phosphatase, alongside radiographs, to assess treatment
- Surgical intervention for bone deformities. This may include osteotomies or epiphysiodesis.
Subtypes of Rickets
| Subtype | Description | Laboratory features |
|---|---|---|
| Nutritional (Vitamin D-related) rickets | This is caused by vitamin D deficiency (dietary or sunlight) | Low 25-OH-Vitamin D, low calcitriol, variable serum calcium, hypophosphataemia, elevated parathyroid hormone, low urine calcium, and high urine phosphate |
| Vitamin D-dependent rickets type 1 (VDDR-1) | This is caused by 1α-hydroxylase deficiency. This responds to calcitriol. | Normal or high 25-OH vitamin D, low calcitriol, variable serum calcium, low serum phosphate, high parathyroid hormone, low urine calcium, and high urine phosphate |
| Vitamin D-dependent rickets type 2 (VDDR-II) | This is caused by defective calcitriol (vitamin D) receptors. It may be resistant to normal vitamin D | Elevated calcitriol, variaable calcium, hypophosphataemia, high parathyroid hormone, low urine calcium, and high urine phosphate |
| Renal osteomalacia | This is rickets that is superimposed on chronic kidney disease. It is due to impaired phosphate excretion, calcium wasting, and reduced production of calcitriol. | Low calcitriol, normal 25-OH vitamin D, low serum calcium, high serum phosphate, elevated creatinine |
| Hypocalcaemia (calcipenic) rickets | This is caused by hypocalcaemia, particularly in children who are breastfeeding without calcium supplementation or those who are consuming unfortified formulas. | Hypocalcaemia, low urine calcium, high urine phosphate, normal renal function |
| X-linked hypophosphatemic rickets (XLHR) | This is caused by overproduction of FGF-23, which stimulates phosphate excretion and inhibits 1α-hydroxylase | Normal 25-OH vitamin D, low calcitriol, low serum phosphate, high urinary phosphate |
| Autosomal dominant hereditary rickets (ADHR) and autosomal recessive hereditary rickets | This has a similar profile to and management as XLHR | |
| Hereditary Hypophosphatemic Rickets with Hypercalciuria (HHRH) | This is caused by a defective sodium-phosphate cotransporter in the proximal tubule, which results in hypophosphatemia and hypercalcaemia |