Updated: 6/3/2019

Rickets / Osteomalacia

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Snapshot
  • A 6-year-old boy is brought to his pediatrician by his parents due to poor growth, weakness, and abnormal gait. On physical exam, there is bowing of the legs and tenderness upon palpation of the lower extremity. Laboratory testing is significant for a decreased serum calcium and phosphate levels and elevated parathyroid hormone and serum alkaline phosphatase levels. (Rickets secondary to vitamin D defiency)
 
Introduction
  • Clinical definition
    • osteomalacia
      • a condition due to defective mineralization of osteoid
    • rickets
      • a condition due to defective mineralization of cartilage in the epiphyseal growth plates
  • Epidemiology
    • demographics
      • children can have both osteomalacia and rickets
      • adults can only have osteomalacia since their growth plates have been fused
    • risk factors
      • vitamin D deficiency secondary to
        • poor dietary intake and sun exposure
        • malabsorption
          • e.g., inflammatory bowel disease and gastrointestinal bypass surgery
        • genetic causes that result in
          • vitamin D deficiency and vitamin D resistance
      • primary hypophosphatemia
        • e.g., X-linked hypophosphatemic rickets and autosomal dominant hypophosphatemic rickets
  • Etiology
    • vitamin D deficiency
    • hypophosphatemia
    • chronic kidney disease
      • e.g., metabolic acidosis and decreased 1,25-dihydroxyvitamin D synthesis
    • renal tubular acidosis
      • proximal (type II) renal tubular acidosis/Fanconi syndrome
        • secondary to phosphate wasting, metabolic acidosis which increases calcium loss, and secondary hyperparathyroidism
    • inhibitors of bone mineralization
      • e.g., bisphosphonates, alimunum, and fluoride
    • hypophosphatasia
      • a tissue non-specific alkaline phosphatase (TNSALP) gene mutation that leads to the accumulation of pyrophosphate
        • pyrophosphate inhibits bone mineralization
  • Pathogenesis
    • impaired mineralization of osteoid (osteomalacia) and/or cartilage at the epiphyseal plates (rickets)
  • Prognosis
    • depends on the etiology
Presentation
  • Symptoms
    • bone and joint pain
    • muscle weakness
    • difficulty with walking
    • fractures
  • Physical exam
    • pediatric
      • bowed legs
      • rachitic rosary line
        • costochondral thickenings
      • Harrison's groove
        • depression along line of diaphragmatic insertion into rib cage
      • kyphosis 
        • as well as lordosis and scoliosis
      • poor growth
    • bone tenderness to palpation
Imaging
  • Radiography 
    • indication
      • perform in patients with a clinical presentation concerning for osteomalacia or rickets
    • findings
      • osteomalacia
        • reduced bone mineral density
          • a non-specific finding
        • inability to radiologically distinguish vertebral body trabeculae 
          • the film appears poor quality
        • Looser pseudofractures, fissues, or narrow radiolucent lines
          • characteristic radiologic findings
      • rickets
        • perform an anteriorposterior radiograph in skeletal areas that are rapidly growing (e.g., knee or wrist)
          • osteopenia
          • metaphysis may appear frayed and widened
          • distal physis may appear widened
          • bones of the arms and legs may have angular defomities
Studies
  • Labs
    • highly dependent on the cause
      • e.g., patients with vitamin D deficiency will have decreased 25-hydroxyvitamin D
 
Laboratory Abnormalities in Rickets/Osteomalacia
Etiology
Serum Phosphate
Serum Calcium
Serum Alkaline Phosphatase
Parathydroid Hormone
Vitamin D deficiency Decreased or normal
Decreased or normal
Elevated
Elevated
Urinary phosphate wasting Decreased
Normal
Elevated or normal
Normal
Proximal (type II) renal tubular acidosis Decreased
Normal
Normal
Normal
Hypophosphatasia Normal
Normal
Decreased
Normal
 
Differential
  • Child abuse
  • Osteogenesis imperfecta 
  • Osteoporosis
  • Paget disease of bone
  • Multiple myeloma
  • Vitamin D resistant rickets 
    • normal vitamin D and normal PTH
 
Laboratory Abnormalities in Select Bone Disorders
Etiology
Serum Phosphate
Serum Calcium
Serum Alkaline Phosphatase
Parathyroid Hormone
Osteoporosis
Normal Normal or decreased Normal Normal
Paget disease of the bone Normal Normal Elevated Normal
Osteitis fibrosa cystica
Primary
hyperparathyroidism
 • decreased

Secondary
hyperparathyroidism
 • increased

Primary
hyperparathyroidism
 • increased

Secondary
hyperparathyroidism
 • decreased

Primary and secondary hyperparathyroidism
 • increased

Primary and secondary hyperparathyroidism
 • increased
Hypervitaminosis D Increased Increased Normal Decreased
 
Treatment
  • Medical
    • treatment is directed against the underlying cause for example
      • vitamin D supplemention
        • indication in patients with
          • vitamin D deficiency
          • hereditary hypophosphatemic rickets along with phosphate supplementation
          • osteomalacia of renal tubular acidosis along with sodium or potassium citrate
Complications
  • Fractures
  • Growth abnormalities
 

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Questions (3)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M2.OR.17) A 2-year-old boy presents to the pediatrician for a well-child visit. The child has been doing well and this is his first visit to a pediatrician after being adopted. His parents state that he is doing well and wanted him to generally be checked out. His temperature is 97.0°F (36.1°C), blood pressure is 100/65 mm Hg, pulse is 100/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for the finding in Figure A. Laboratory values are ordered as seen below.

Serum:
Ca2+: 9.1 mg/dL
Phosphorus: 1.1 mg/dL
Alkaline phosphatase: 462 U/L
Parathyroid hormone: 23 pg/mL (N = 10-55)
1,25-dihydroxyvitamin D: 22 pmol/L (N = 15-30)

What is the most likely diagnosis? Review Topic

QID: 104464
FIGURES:
1

Pseudohypoparathyroidism

67%

(16/24)

2

Renal osteodystrophy

17%

(4/24)

3

Vitamin D deficiency rickets

4%

(1/24)

4

Vitamin D resistant rickets

4%

(1/24)

5

Type II vitamin D dependent rickets

4%

(1/24)

M2

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PREFERRED RESPONSE 4

(M2.OR.22) A 70-year-old woman presents to the office for a yearly physical. She states she has recently started experiencing pain in her legs and her back. Last year, she experienced a fracture of her left arm while trying to lift groceries. The patient states that she does not consume any dairy and does not go outside often because of the pain in her legs and back. Of note, she takes carbamazepine for seizures. On exam, her vitals are within normal limits. You suspect the patient might have osteomalacia. Testing for which of the following is the next best step to confirm your suspicion? Review Topic

QID: 104347
1

7-dehydrocholesterol

0%

(0/0)

2

25-hydroxyvitamin D

0%

(0/0)

3

1,25-hydroxyvitamin D

0%

(0/0)

4

Pre-vitamin D3

0%

(0/0)

5

Dietary vitamin D2

0%

(0/0)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2
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