Rickets

Rickets happens when the body can’t get or use enough calcium, phosphorus, or vitamin D to build strong bones. This can be due to nutrition, problems with absorption, or genetic conditions.

Nutritional Rickets (Most common type)

• Often prevented by giving infants 400 units of vitamin D each day.
• Caused by severe vitamin D deficiency (not enough sunlight, not enough in diet, problems absorbing it, or problems activating it in the liver or kidneys) and/or severe calcium deficiency (poor diet or trouble absorbing calcium).

X-linked Hypophosphatemia (XLH)

• Genetic condition causing low phosphorus levels and rickets.
• Inherited from one parent; affects phosphorus balance in the body.

Hereditary Hypophosphatemic Rickets with Hypercalciuria (HHRH)

• Caused by 2 copies of a change in the SLC34AC gene.
• Leads to rickets, low phosphorus, high active vitamin D, and excess calcium in urine.
• Very rare: about 1 in 250,000 people affected; carriers may have high urine calcium and sometimes kidney stones.

Hereditary Vitamin D Dependent Rickets (HVDDR)

• Type 1A: Caused by 2 copies of a change in the CYP27B1 gene. The body can’t activate vitamin D, so it can’t absorb calcium and phosphorus well.
• Type 1B: Caused by changes in the CYP2R1 gene. The body can’t make the storage form of vitamin D.
• Type 2A & 2B: The body makes active vitamin D but doesn’t respond to it (“vitamin D resistance”), leading to rickets and often baldness or hair loss.
• Type 3: Caused by a change in the CYP3A4 gene, which breaks down vitamin D too quickly.

Other Rare Types

• Linked to different genetic changes that affect bone and mineral balance.

Rickets can affect bones, growth, teeth, and overall development. Signs may include:

• Widened wrists
• Bowed legs or “knock knees” (in children who walk)
• Rachitic rosary – small, bead-like bumps along the ribs
• Bone pain
• Slow growth or short height
• Teeth coming in later than expected
• Low muscle tone
• Delayed walking or running
• Soft skull bones or a “soft spot” that closes late
• Dental problems, such as weak enamel or frequent infections
• Low bone density and broken bones
• Changes in blood levels of calcium, vitamin D, phosphorus, or alkaline phosphatase

Low calcium levels (hypocalcemia) can also cause tingling, muscle cramps, breathing problems, seizures, and, in rare cases, heart problems.

If your child shows signs of rickets, the doctor may order blood tests and x-rays (often of the wrists and legs). These tests check levels of calcium, phosphorus, vitamin D (both storage and active forms), parathyroid hormone (PTH), and alkaline phosphatase (ALP). In some cases, genetic testing may be recommended to find the exact cause.

Treatment depends on the cause, but the main goals are to:

• Heal the rickets and strengthen bones
• Normalize calcium, phosphorus, and vitamin D levels
• Relieve pain
• Correct bone changes and improve growth
• Support overall quality of life

Examples of treatment based on type:

• Nutritional rickets – Vitamin D and calcium supplements; sometimes active vitamin D if needed. If absorption is the problem, the underlying issue is treated.
• X-linked hypophosphatemic rickets (XLH) – Raise phosphate levels using phosphate supplements and active vitamin D (calcitriol). Some children may receive burosumab injections every 2–4 weeks to lower FGF23 levels.
• Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) – Phosphate supplements.
• Hereditary vitamin D dependent rickets (HVDDR) –
  • Type 1A: Active vitamin D and calcium
  • Type 1B: Storage vitamin D
  • Type 2A & 2B: High doses of active vitamin D, sometimes with calcium
  • Type 3: High doses of storage vitamin D

If rickets is suspected, our team may recommend blood work, urine tests, and/or imaging before or at your child’s first visit. We’ll review all the results together and create a personalized treatment plan based on the cause, lab findings, and your child’s symptoms.