Overview
Definition:
Vitamin D deficiency is a condition characterized by insufficient levels of vitamin D in the body, leading to impaired calcium and phosphate absorption, and ultimately affecting bone health
It is defined by serum 25-hydroxyvitamin D [25(OH)D] levels below 20 ng/mL (50 nmol/L)
Deficiency severe enough to cause rickets is defined as 25(OH)D < 10 ng/mL (25 nmol/L).
Epidemiology:
Vitamin D deficiency is highly prevalent globally, affecting a significant proportion of infants, children, and adolescents
Factors contributing to its prevalence in India include limited sun exposure due to cultural practices and urbanization, darker skin pigmentation, inadequate dietary intake, and malabsorption syndromes
Neonates and exclusively breastfed infants are particularly at risk.
Clinical Significance:
Vitamin D is crucial for calcium homeostasis, bone mineralization, immune function, and cell growth
Deficiency can lead to rickets in children, characterized by skeletal deformities, impaired growth, and increased risk of fractures
It also has implications for neuromuscular function, and potentially for chronic diseases later in life
Early diagnosis and appropriate management are vital for preventing long-term skeletal and systemic complications.
Clinical Presentation
Symptoms:
Infants: Irritability
Poor feeding
Muscle weakness (hypotonia)
Delayed motor milestones
Older children: Bone pain, particularly in legs, back, and pelvis
Muscle aches and cramps
Fractures with minimal trauma (pathological fractures)
Growth retardation and short stature
Delayed dentition and dental enamel defects
In severe cases: Seizures due to hypocalcemia.
Signs:
Infants: Rachitic rosary (nodules on ribs)
Craniotabes (soft skull bones)
Delayed fontanelle closure
Harrison's groove (horizontal groove at lower chest margin)
Older children: Bow legs (genu varum) or knock knees (genu valgum)
Waddling gait
Skeletal deformities (e.g., kyphoscoliosis, pelvic deformities)
Tenderness over bones
Signs of hypocalcemia: Chvostek's sign, Trousseau's sign, tetany.
Diagnostic Criteria:
Diagnosis is primarily based on low serum 25-hydroxyvitamin D [25(OH)D] levels
The Indian Academy of Pediatrics (IAP) guidelines recommend the following for deficiency: Severe deficiency (<10 ng/mL or <25 nmol/L)
Insufficiency (10-20 ng/mL or 25-50 nmol/L)
Sufficiency (≥20 ng/mL or ≥50 nmol/L)
In cases of suspected rickets, serum calcium, phosphate, alkaline phosphatase, and PTH levels are also essential
Radiographs may show characteristic features of rickets.
Diagnostic Approach
History Taking:
Detailed birth history (preterm, low birth weight)
Feeding history (breastfeeding duration, formula type, intake of vitamin D-fortified foods)
Sun exposure habits (time spent outdoors, use of sunscreens, clothing)
Maternal vitamin D status during pregnancy
History of chronic diseases affecting absorption (e.g., cystic fibrosis, celiac disease)
Family history of bone diseases or vitamin D deficiency
Symptoms suggestive of rickets or hypocalcemia.
Physical Examination:
General assessment: Growth parameters (height, weight, head circumference)
Assessment for signs of skeletal deformities (bowing of legs, widening of wrists/ankles, rachitic rosary)
Neurological examination for signs of hypocalcemic seizures or neuromuscular irritability
Assess for muscle weakness and gait abnormalities
Palpate bones for tenderness.
Investigations:
Serum 25-hydroxyvitamin D [25(OH)D] is the primary diagnostic test
Serum calcium, phosphate, alkaline phosphatase (elevated in rickets), and parathyroid hormone (PTH, elevated in secondary hyperparathyroidism due to vitamin D deficiency) are crucial
In cases of significant hypocalcemia, serum magnesium and albumin levels should also be checked
X-rays of the wrist and knee are often used to assess for rachitic changes.
Differential Diagnosis:
Other causes of bone pain and skeletal deformities: Juvenile idiopathic arthritis
Osteomyelitis
Malignancies
Other metabolic bone diseases like hypophosphatemic rickets
Osteogenesis imperfecta
Nutritional deficiencies other than vitamin D (e.g., calcium, phosphorus)
Pseudofractures can mimic osteomalacia.
Management
Initial Management:
For severe deficiency (<10 ng/mL or <25 nmol/L) and symptomatic rickets, immediate correction of deficiency is paramount
This involves high-dose vitamin D therapy along with calcium supplementation if hypocalcemia is present
Management should be guided by a pediatrician or pediatric endocrinologist
Monitoring of serum calcium and phosphate is critical during high-dose therapy.
Medical Management:
Dosing strategies vary based on age and severity
IAP recommendations generally follow: \n**Treatment of Vitamin D Deficiency (<20 ng/mL or <50 nmol/L):**\n* **Infants (<1 year):** 1,000-2,000 IU/day of vitamin D (cholecalciferol or ergocalciferol) for 6-12 weeks, followed by maintenance dose of 400-1,000 IU/day
\n* **Children (1-18 years):** 2,000-4,000 IU/day for 6-12 weeks, followed by maintenance dose of 600-1,000 IU/day
\n**Treatment of Severe Vitamin D Deficiency (<10 ng/mL or <25 nmol/L) with Rickets:**\n* **Infants (<1 year):** A single large dose (e.g., 50,000 IU cholecalciferol orally once, or 100,000 IU IM once) followed by daily therapy
Alternatively, 1,000-2,000 IU/day for 8-12 weeks
\n* **Children (1-18 years):** Single dose of 50,000-100,000 IU cholecalciferol orally weekly for 4-8 weeks, or 2,000-5,000 IU/day for 8-12 weeks
\n**Calcium Supplementation:** If serum calcium is low, administer calcium supplements (e.g., calcium carbonate, calcium citrate) to achieve normal levels
Dose: 50-100 mg/kg/day elemental calcium divided into 2-3 doses
\n**Maintenance Therapy:** Once normalized, continue with adequate daily intake (400-1000 IU/day for infants, 600-1000 IU/day for older children and adolescents).
Surgical Management:
Surgery is generally not the primary management for vitamin D deficiency
However, in cases of severe, neglected rickets with significant skeletal deformities (e.g., severe bowing of legs), corrective osteotomies may be considered much later, once bone mineralization has improved and is stable.
Supportive Care:
Adequate calcium intake through diet or supplements is crucial
Ensuring sufficient sun exposure (while balancing risks of sunburn and skin cancer) is a cornerstone of prevention and management
Education on dietary sources of vitamin D and fortified foods is important
Regular monitoring of growth and bone health is necessary.
Age Specific Dosing
Neonatal Dosing:
For exclusively breastfed neonates and infants, routine prophylaxis of 400 IU/day of vitamin D is recommended from birth
If maternal vitamin D status is unknown or deficient, consider higher doses for the infant.
Infantile Dosing:
Treatment for deficiency in infants (<1 year) typically involves 1,000-2,000 IU/day for 6-12 weeks, followed by 400-1,000 IU/day for maintenance
For severe deficiency with rickets, a single large dose of 50,000-100,000 IU or daily 1,000-2,000 IU for 8-12 weeks may be used, with careful monitoring.
Childhood Dosing:
Children (1-18 years) with deficiency are usually treated with 2,000-4,000 IU/day for 6-12 weeks, followed by 600-1,000 IU/day for maintenance
Severe deficiency with rickets might require 2,000-5,000 IU/day for 8-12 weeks or weekly high doses.
Adolescent Dosing:
Adolescents may require higher doses due to increased bone mass accumulation and potential for lifestyle factors affecting vitamin D status
Maintenance doses of 600-1,000 IU/day are typically recommended
Treatment doses are similar to younger children but may extend longer if deficiency is severe.
Complications
Early Complications:
Hypocalcemia: Can manifest as tetany, muscle cramps, paresthesias, and in severe cases, seizures
Cardiac arrhythmias
Respiratory distress due to muscle weakness
Fractures: Pathological fractures of long bones and vertebrae can occur with minimal trauma.
Late Complications:
Permanent skeletal deformities: Bowed legs, knock knees, spinal deformities, pelvic deformities affecting gait and posture
Stunted growth and short stature
Dental abnormalities: Delayed eruption, enamel hypoplasia, increased caries
Increased susceptibility to infections
Potential long-term risks for osteoporosis, cardiovascular disease, and certain cancers, though direct causality is still under investigation.
Prevention Strategies:
Routine vitamin D supplementation for all infants, especially those breastfed
Adequate sun exposure in infants and children, balanced with safety
Consumption of vitamin D-fortified foods (milk, cereals)
Public health campaigns to raise awareness about vitamin D deficiency
Screening high-risk populations
Ensuring adequate dietary calcium intake.
Prognosis
Factors Affecting Prognosis:
Severity and duration of deficiency
Timeliness and adequacy of treatment
Presence of co-morbidities affecting calcium/vitamin D absorption or metabolism
Adherence to treatment and maintenance therapy
Genetic factors.
Outcomes:
With prompt and appropriate treatment, the prognosis for vitamin D deficiency rickets is generally excellent
Skeletal deformities can improve, and bone mineralization usually normalizes
Long-term monitoring is essential to prevent relapse and ensure optimal bone health
Untreated or delayed treatment can lead to irreversible skeletal damage and chronic health issues.
Follow Up:
Regular follow-up with a pediatrician is crucial
This typically involves: \n1
Rechecking serum 25(OH)D levels 2-3 months after initiating treatment to assess response
\n2
Monitoring serum calcium, phosphate, and alkaline phosphatase levels to ensure normalization and avoid toxicity
\n3
Assessing for resolution of symptoms and improvement in growth and skeletal development
\n4
Ensuring compliance with maintenance vitamin D supplementation
\n5
Periodic reassessment of vitamin D status, especially in children with ongoing risk factors.
Key Points
Exam Focus:
DNB/NEET SS examiners frequently test knowledge on vitamin D deficiency diagnosis and management in children
Key areas include identifying risk factors, interpreting 25(OH)D levels, understanding IAP/national guidelines for dosing (especially age-based and severity-based), and recognizing complications like rickets and hypocalcemia.
Clinical Pearls:
Always consider vitamin D deficiency in infants with poor feeding or irritability, and in children with bone pain, fractures, or growth faltering
Remember to assess calcium levels alongside vitamin D
Maintenance therapy is as important as the initial treatment
Sunlight exposure is beneficial but should be balanced with skin cancer prevention
Darker skin tones require longer sun exposure to synthesize equivalent amounts of vitamin D.
Common Mistakes:
Underestimating the prevalence of vitamin D deficiency, especially in India
Inadequate dosing or duration of treatment
Forgetting to supplement calcium when hypocalcemia is present
Failing to ensure adequate maintenance therapy, leading to relapse
Misinterpreting biochemical parameters without considering the clinical context
Over-reliance on sunlight alone without proper guidance.