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Diagnosis of XLH when there is a family history of XLH
By: Larry
Winger, Ph.D., PGCE
& Scott
Schmitz
Following are the published age-specific
values for inorganic phosphorus in serum or plasma of five separate laboratories.
It is important to use age-matched controls when seeking to determine relative
phosphorus levels in children with a known family history of XLH.
Note these Equivalencies for Serum Inorganic Phosphorus Levels:
SIGMA provides an inorganic Phosphorus reference standard which is :
20mcg per ml equivalent to 645 nanomoles per ml
Since a deciLitre is 100 ml, this is the same as saying:
2000mcg/dL or 2mg/dL or 645 mcmoles/L or 0.645mmol/L
Therefore, 1mg/dL is the same as 0.322 mmol/L
From PEDIATRIC REFERENCE RANGES, 3rd edition, by Steven J. Soldin, published
by AACC Press, Washington, DC, 1999 pages 145-146, a text outlining normal levels
of testable substances in children. By kind permission of the publisher.
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PHOSPHORUS
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Male
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Female
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Test
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Age
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n
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mg/dL
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mmol/L
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n
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mg/dL
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mmol/L
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1.
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1-30d
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62
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3.9 - 6.9
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1.25 - 2.25
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66
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4.3 - 7.7
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1.40 - 2.50
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31 - 365d
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83
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3.5 - 6.6
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1.15 - 2.15
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66
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3.7 - 6.5
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1.20 - 2.10
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1 - 3y
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126
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3.1 - 6.0
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1.00 - 1.95
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119
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3.4 - 6.0
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1.10 - 1.95
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4 - 6y
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112
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3.3 - 5.6
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1.05 - 1.80
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107
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3.2 - 5.5
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1.05 - 1.80
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7 - 9y
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117
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3.0 - 5.4
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0.95 - 1.75
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107
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3.1 - 5.5
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1.00 - 1.80
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10 - 12y
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135
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3.2 - 5.7
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1.05 - 1.85
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115
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3.3 - 5.3
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1.05 - 1.70
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13 - 15y
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109
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2.9 - 5.1
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0.95 - 1.65
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110
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2.8 - 4.8
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0.90 - 1.55
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16 - 18y
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95
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2.7 - 4.9
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0.85 - 1.60
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122
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2.5 - 4.8
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0.80 - 1.55
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2.
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0 - 5d
(<2.5 kg)
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50
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4.6 - 8.0
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1.50 - 2.60
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50
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4.6 - 8.0
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1.50 - 2.60
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1 - 3y
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50
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3.9 - 6.5
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1.25 - 2.10
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50
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3.9 - 6.5
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1.25 - 2.10
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4 - 6y
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38
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4.0 - 5.4
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1.30 - 1.75
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38
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4.0 - 5.4
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1.30 - 1.75
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7 - 9y
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72
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3.7 - 5.6
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1.20 - 1.80
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72
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3.7 - 5.6
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1.20 - 1.80
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10 - 11y
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62
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3.7 - 5.6
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1.20 - 1.80
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62
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3.7 - 5.6
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1.20 - 1.80
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12 - 13y
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73
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3.3 - 5.4
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1.05 - 1.75
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73
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3.3 - 5.4
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1.05 - 1.75
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14 - 15y
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91
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2.9 - 5.4
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0.95 - 1.75
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91
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2.9 - 5.4
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0.95 - 1.75
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16 - 19y
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107
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2.8 - 4.6
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0.90 - 1.50
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107
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2.8 - 4.6
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0.90 - 1.50
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3.
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0 - 30d
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181
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2.7 - 7.2
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0.87 - 2.33
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140
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3.0 - 8.0
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0.97 - 2.58
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31 - 90d
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87
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3.0 - 6.8
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0.97 - 2.20
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84
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3.0 - 7.5
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0.97 - 2.42
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3 - 12mo
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109
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3.0 - 6.9
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0.97 - 2.23
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119
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2.5 - 7.0
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0.81 - 2.26
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13 - 24mo
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69
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2.5 - 6.4
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0.81 - 2.07
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78
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3.0 - 6.5
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0.97 - 2.10
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2 - <13y
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148
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3.0 - 6.0
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0.97 - 1.94
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254
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2.5 - 6.0
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0.81 - 1.94
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13 - <16y
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175
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3.0 - 5.4
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0.97 - 1.74
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72
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3.0 - 5.6
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0.97 - 1.81
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16 - <18y
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72
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3.0 - 5.2
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0.97 - 1.68
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196
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3.0 - 4.8
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0.97 - 1.55
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Specimen:
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1., 2., 3., Serum or Plasma
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Reference:
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1. Soldin SJ, Hicks JM, Bailey J, et al. Pediatric reference ranges
for phosphate on the Hitachi 747 analyzer. Clin. Chem. 1997; 43:S198.
(Abstract)
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2. Lockitch G, Halstead AC, Albersheim S, et al. Age and sex specific
pediatric reference intervals for biochemistry analytes as measured
with the Ektachem 700 analyzer. Clin. Chem 1988;34:1622-5.
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3. Soldin SJ, Hunt C, Hicks JM. Pediatric reference ranges for Phosphorus
on the Vitros 500 Analyzer. Clin Chem 1999;45:A22 (Abstract)
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Method:
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1. Hitachi 747 using ammonium molybdate method (Boehringer-Mannheim,
Diagnostics, Indianapolis, IN).
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2., 3. Ektachem 700 (2) and 500 (3) using ammonium molybdate method.
(Johnson & Johnson, Rochester, NY.)
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Comments:
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1., 3. Study used hospitalized patients and a computerized approach
to removing outliers. Values are 2.5 - 97.5th percentiles.
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2. Study used normal healthy children. Values are 2.5 - 97.5th percentiles
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In this table, n is the number of subjects assessed in each
age category.
As reported through a contact in [MEDLAB-L], the Medical Laboratory mailing
list, February, 2000, from a laboratory in the USA.
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Patient Age
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Inorganic Phosphorus Normals
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Less than 6 Days
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4.0-9.0 MG/DL
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6 Days - 2 Years
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4.0-8.0 MG/DL
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2 Years - 12 Years
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3.0-6.0 MG/DL
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12 Years - 64 Years
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2.0-5.9 MG/DL
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over 64 Years
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2.1-4.3 MG/DL
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As reported in the Medical School, University of Iowa, Pathology Handbook
current
as of September 20, 2001
http://www.medicine.uiowa.edu/path_handbook/Appendix/Heme/PEDIATRIC_NORMALS.html#Chemistry
Specifically:
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Patient Age
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Inorganic Phosphorus Normals
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Newborn:
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4.2 - 9.0 mg/dL
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1y:
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3.8 - 6.2 mg/dL
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2y - 5y:
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3.5 - 6.8 mg/dL
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Typically, Clinical Chemistry laboratories read a reference set of standards
(eg 1, 5 and 15 mg/dL from SIGMA Biochemicals and Reagents) to produce a "standard
curve". The so-called 'critical value' for reporting directly to physicians
requesting a test for phosphate (ie inorganic phosphorus) is <1mg/dL. Naturally,
this value is based on the normal adult range.
Also, as of September 2001, the BioScience Organization provides these values
in their Clinical Chemistry Atlas.
http://www.bioscience.org/atlases/clinical/chemist/o-s.htm
Serum Inorganic Phosphorus
Adults 2.3-4.7 mg/dL or 0.74-1.52 mmol/L
Children 4.0-7.0 mg/dL or 1.29-2.26 mmol/L
Last modified Aug 8, 2007
XLH is also known as X-Linked Hypophosphatemia (sometimes also
spelled as hypophosphataemia), X-Linked Hypophosphatemic Rickets,
Familial Hypophosphatemia, Vitamin D-Resistant Rickets (VDRR)
Rickets and even Genetic Rickets. Its notable characteristics are
bowed legs, short stature, poor teeth formation causing spotaneous
dental abscesses, and low blood phosphorus levels.
© 2002-2007,
The XLH Network Inc.
The authors of this web site are not medical professionals, and this
information does not substitute for medical care. Information on
these pages is based on biomedical research, published in
peer-reviewed journals, and international research conferences.
Additionally, in some cases anecdotal information is provided by
subscribers of the F-HYPDRR group, a mailing list for The XLH Network
Inc. A complete web-site
bibliography
is available. Please read our full
disclaimer.
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