What are Presentations for Rickets?

A 14 month-old Africian American male comes to clinic for poor weight and height gain. He was a full-term infant with weight and height in the 90%, and head circumference at the 50% until 9 months of age when he began to lose weight and height and cross percentiles on the growth charts.

The past medical history revealed that he was exclusively breastfed until 6 months of age with some infant formula since. He takes little baby food of a limited variety. He is a picky eater and refuses cow’s milk and bread products. He eats fruits, vegetables or meat. He refuses vitamin supplements. His mother eats a regular balanced diet.
The review of systems is negative including no abnormal stooling or urination.
His past family history is normal.
His pertinent physical exam shows his vital signs are normal. His weight and height were at the 3% while his head was at the 50%. He was described as clingy and fearful. Head shows slight frontal bossing. Rib cage has mild palpable swelling at the costovertebral junctions. His abdomen is protuberant with normal bowel sounds and no organomegaly. His extremeties have widened wrists and ankles. There is no bowing of his lower extremeties, but he has a trundling gait. He has no peripheral edema. His neurological examination is normal with good tone.
The patient was admitted for evaluation and initiation of treatment.
The laboratory evaluation included: calcium was low at 6.5 mg/dl (normal = 8.8-10.6), phosphorus was low at 3.0 mg/dl (normal = 3.8-6.2), and alkaline phosphatase was high at 1917 U/l (normal = 104-345). Vitamin D 25-OH was low normal at 12.0 ng/ml (normal = 10-68) and Vitamin D 1,25-OH was high at 87 pg/ml (normal = 15-75), parathyroid hormone was high at 470 pg/ml (normal = 10-65). Other laboratory evaluations including urine calcium and phosphorus were normal.
The diagnosis of vitamin D deficiency rickets was made.
The patient’s clinical course included treatment with calcium, calcitrol, and intensive nutritional and behavioral therapy which was continued as an outpatient.

Figure 3 – 12-06-04 – AP radiograph of the chest showing promient costochondral joints bilaterally – a “Rachitic Rosary.”

Figure 4 – 12-06-04 – AP and lateral radiographs of the left wrist shows in the distal radius and ulna metaphyseal splaying and partial loss of the zone of provisional calcification bilaterally. The right wrist had a similar appearance.

Discussion
When the osteoid cells in bones fail to calcify in a growing person this is termed Rickets. If this occurs in an adult it is called osteomalacia.

Ultraviolet light in the skin changes cholesterol to Vitamin D3 (i.e. cholecalciferol). Vitamin D3 then is hydroxylated in the liver to make Vitamin D 25-OH (i.e. calcidiol, the circulating reserve metabolite). It then undergoes hydroxylation again in the kidney to Vitamin D 1,25-OH (i.e. calcitriol, the active metabolite).

Vitamin D 1,25-OH helps calcium and phosphorous absorption from the intestine, increases kidney reabsorption of phosphorus, and it causes calcium and phosphorus to be released from the bone. Increasing the concentrations of calcium and phosphorus in extracellular fluid causes osteoid cells to calcify. Parathyroid hormone increases the 1-hydroxylation step of vitamin D metabolism and thereby helps regulate calcium metabolism.

Therefore if Vitamin D 1,25-OH is low, hypocalcemia develops, causing parathyroid hormone to be excessively released. This produces loss of phosphorus by the kidney and more difficulties with calcium homeostasis. The parathyroid hormone causes the calcium extracellular concentration to return to normal but with a low phosphorus level. This causes osteoblasts to reabsorb bone so phosphorus metabolism is normalized. Alkaline phosphatase produced by ostoblast cells also leaks to the extracellular fluids causing elevation of its level. Therefore most children with rickets, have a normal to low calcium, low phosphorus, high parathyroid hormone and high alkaline phosphatase levels. Vitamin D 25-OH is usually low with Vitamin D 1,25-OH being low, normal, or high.

Severe rickets in the US is rare but there are high-risk populations such as infants who are exclusively breast-fed without supplementation of Vitamin D (because there is little Vitamin D in breast-milk), dark-skinned individuals (because of decreased conversion of the steroid into the skin), and people with little sun exposure such as those in northern climates, excessive smog exposure, or living in institutions.

Commercially produced milk and infant formulas are fortified with Vitamin D. Infants and children should receive between 200-400 IU daily.

The best treatment is prevention but if rickets occurs adminsistration of vitamin D and calcium for several weeks is needed. Hypocalcemia caused by remineralization of the bone matrix is a potential side effect of treatment called hungry bone syndrome.

Learning Point
Clinical and radiographic presentations of rickets include:

  • General

    • Generalized malnutrition and lack of normal physiologic growth
    • Anorexia
    • Generalized hypotonia – cause unknown
    • Tetany – caused by hypocalcemia, may be precipitated by infection
  • Skeletal

    • Craniotabes – especially along the suture line
    • Skull thickening – particularly frontal area with delayed closure of anterior fontanelle
    • Rachitic Rosary – prominance of the costochondral junctions of the ribs
    • Harrison’s groove – flaring of the ribs over the diaphragm caused by muscles pulling on weak bones
    • Pectus carinatum – caused by muscles pulling on weak bones
    • Kyphoscoliosis
    • Widened wrists and ankles – knobby deformity of epiphysis caused by metaphyseal splaying
    • Genu varum or genu valgum
    • Fractures – especially greenstick fractures

Questions for Further Discussion
1. What other nutritional deficiencies should be looked for?
2. How could rickets and malnutrition have been prevented?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Gunn VL, Nechyba C. The Harriet Lane Handbook. 16th. Edit. Mosby Publications: St. Louis. 2002:460.

Fineberg L. Rickets. eMedicine.
Available from the Internet at http://www.emedicine.com/ped/topic2014.htm (rev. 12/10/03, cited 11/18/04).

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:2156-2160.

Author
Donna M. D’Alessandro, MD
Associate Professor of Pediatrics, Children’s Hospital of Iowa

Date
December 6, 2004