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Key messages

  • Normal pathology values are readily available for healthy term infants.
  • Consider laboratory error if spurious result are returned for a well baby.
  • Where possible, use local laboratory reference ranges.
  • Laboratory tests are only useful if they guide management.
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    Please note that all guidance is currently under review and some may be out of date. We recommend that you also refer to more contemporaneous evidence in the interim.

    Normal laboratory values are reference ranges used by clinicians to interpret results of laboratory tests.

    In general, normal pathology values are readily available for healthy term infants. As (extreme) prematurity is a pathological condition in itself, be cautious when using the concept of ‘normal’.

    In most cases, when considering the correction of ‘abnormal’ values, it is wise to consider the following:

    • Is this due to sampling or laboratory error?
    • Is the baby symptomatic?
    • What is the evidence that correcting the abnormality is beneficial?
    • Is there any risk or danger in correcting an abnormal result?

    It is always advisable to keep in mind the reference ranges from your own laboratory as they will be analyser or population-specific. This is particularly important, for example, with respect to coagulation profiles. If your laboratory does not provide reference ranges for newborns or subsets thereof, the following may be helpful.

    N.B. mm/L = micromol/litre.

    Term infants (age of life)

    Value
    Cord
    1-12 hr
    12-24 hr
    24-48 hr
    48-72 hr
    3-10 d
    Na 
    (mEq/L)
    147
    (126-166)
    143 (124-156) 145 (132-159) 148 (134-160) 149 (139-162)  

    (mEq/L)
    7.8
    (5.6-12)
    6.4 (5.3-7.3) 6.3 (5.3-8.9) 6.0 (5.2-7.3) 5.9 (5.0-7.7)  
    Cl 
    (mEq/L)
    103
    (98-110)
    101 (80-111) 103 (87-114) 102 (92-114) 103 (93-112)  
    Ca (mmol/L) 2.33
    (2.1-2.8)
    2.1 (1.8-2.3) 1.95 (1.7-2.4) 2.0 (1.5-2.5) 1.98 (1.5-2.4)  
    Ca (I) (mmol/L)   1.05-1.37 1.05-1.37 1.05-1.37 1.10-1.44 1.20-1.48
    PO4 (mmol/L) 1.8
    (1.2-2.6)
    1.97 (1.1-2.8) 1.84 (0.9-2.6) 1.91 (1.0-2.8) 1.87 (0.9-2.5)  
    Mg (mmol/L)     0.72-1.00   0.81-1.05 0.78-1.02
    Urea (mmol/L) 10.4
    (7.5-14.3)
    9.6 (2.9-12.1) 11.8 (3.2-22.5) 11.4 (4.6-27.5) 11.1 (5.4-24.3)  
    Creat (mmol/L)       0.04-0.11   0.01-0.09
    CRP 
    (mg/L)
    <7 <7 <7 <7 <7 <7
    Lactate (mmol/L) 1.5-4.5 0.9-2.7 0.8-1.2     0.5-1.4
    Albumin (g/L) 28-43 28-43 28-43 28-43 28-43 30-43
    ALP
    (IU/L)
    28-300 28-300 28-300 28-300 28-300 28-300
    T4 8.2
    (+/-1.8)
      19.0 (+/-2.1) 19.0 (+/-2.1) 19.0 (+/-2.1) 15.9 (+/-3.0)
    TSH     3.0-120 3.0-30   0.3-10
    Cortisol (nano
    mol/L)
    200-700 200-700 200-700      
    17-OHP (nano
    mol/L)
            0.7-12.4 0.7-12.4
    Hb (g/L) 168   184   178 170
    Hct (%) 53   58   55 54
    MCV 107   108   99 98
    Retic (%) 3-7   3-7   1-3 0-1
    WCC x 109/L 18.1 (9-30) 22.8 (13-38) 18.9 (9.4-34)     12.2 (5-21)
    Neutro x 109/L 11.1 (6-26) 15.5 (6-28) 11.5 (5-21)     5.5 (1.5-10)
    Lymph x 109/L 5.5 (2-11) 5.5 (2-11) 5.8 (2-11.5)     5.0 (2-17)
    Mono x 109/L 1.1 1.2 1.1     1.1
    Eosin x 109/L 0.4 0.5 0.5     0.5
    Platelets (103/mm3 ) 150-350 150-350 150-350 150-350 150-350 150-350
    PT (sec)   11-14 11-14 11-14 11-14 11-14
    APTT (sec)   23-35 23-35 23-35 23-35 23-35
    FBG (mg/dL)   200-400 200-400 200-400 200-400 200-400
    Capillary refill   < 3 seconds < 3 seconds < 3 seconds < 3 seconds < 3 seconds

     

    Acid base values* - term and preterm infants (by age of life)

    Value
    Cord
    1-12 hr
    12-24 hr
    24-48 hr
    Range**
    pH 7.33 (UV) 7.30 (art) 7.30 (art) 7.39 7.25-7.45
    PCO2 (mmHg) 43 (UV) 39 33 34 35-50
    HCO3 (mEq/L) 21.6 (UV) 18.8 19.5 20 17-28
    PO2 (mmHg) 28 (+/-8) (UV) 62 (+/-13.8) 68 63-87 60-80
    Anion gap <20 <20 <20 <20 8-16

    * Capillary ranges similar except pO2
    ** Very difficult to define, wide variation within/between level III units

    Electrolytes - preterm infants (< 37 weeks) (by day of life)

    Value
    Day 1
    Day 3
    Day 7
    Day 21
    Day 35
    Day 49
    Na (mEq/L) 140 (133-146) 140 (133-146) 140 (133-146) 136 (129-142) 137 (133-148) 137 (133-142)
    K (mEq/L) 5.6 (4.6-6.7) 5.6 (4.6-6.7) 5.6 (4.6-6.7) 5.8 (4.5-7.1) 5.5 (4.5-6.6) 5.7 (4.6-7.1)
    Cl (mEq/L) 108 (100-117) 108 (100-117) 108 (100-117) 108 (102-116) 107 (100-115) 107 (101-115)
    Ca (millimol/L) 2.3 (1.5-2.9) 2.3 (1.5-2.9) 2.3 (1.5-2.9) 2.4 (2.0-2.8) 2.4 (2.2-2.6) 2.4 (2.2-2.7)
    Ca (I) (millimol/L) 0.81-1.41 0.72-1.44 1.04-1.52 (d5) 1.04-1.52 1.04-1.52 1.04-1.52
    PO4 (millimol/L) 2.5 (1.7-3.5) 2.5 (1.7-3.5) 2.5 (1.7-3.5) 2.4 (2.0-2.8) 2.3 (1.8-2.6) 2.2 (1.4-2.7)
    Mg (millimol/L) 0.62-1.02 0.66-1.10 0.75-1.00 0.75-1.00 0.75-1.00 0.75-1.00
    Urea (millimol/L) 3.3 (1.1-9.1) 3.3 (1.1-9.1) 3.3 (1.1-9.1) 4.8 (0.8-11.2) 4.8 (0.7-9.5) 4.8 (0.9-10.9)

    Other biochemistry - preterm infants (by gestation)

    Value
    27 weeks
    29 weeks
    31 weeks
    33 weeks
    35 weeks
    Alb (g/L) 21-33 23-34 22-35 22-35 22-36
    ALP (IU/L) 35-604 119-465 112-450 110-398 113-360
    Creat (micromol/L) day 2 0.08-0.16 0.07-0.14 0.07-0.14 0.05-0.13 0.05-0.13
    Creat (micromol/L) day 7 0.05 -0.11 0.04-0.12 0.04-0.12 0.02-0.11 0.02-0.11
    Creat (micromol/L) day 14 0.04-0.10 0.04-0.10 0.04-0.10 0.02-0.09 0.02-0.09
    Creat (micromol/L) day 21 0.03-0.09 0.03-0.09 0.03-0.09 0.02-0.09 0.02-0.09
    Creat (micromol/L) day 28 0.03-0.08 0.02-0.09 0.02-0.09 0.01-0.06 0.01-0.06

    Haematology - preterm infants (by age)

    Value
    Birth
    12 hours
    24 hours
    1 week
    2 weeks
    1 month
    Hb (g/L) 140 (24 wks)          
      145 (28 wks)          
      150 (34 wks)          
    WCC x 109/L 18.1 (9-30) 22.8 (13--38) 18.9 (9.4-34) 12.2 (5-21) 11.4 (5-20) 10.8 (5-19.5)
    Neutro x 109/L 11.1 (6-26) 15.5 (6-28) 11.5 (5-21) 5.5 (1.5-10) 4.5 (1-9.5) 3.8 (1-9)
    Lymph x 109/L 5.5 (2-11) 5.5 (2-11) 5.8 (2-11.5) 5 (2-17) 5.5 (2-17) 6.0 (2.5-16.5)
    Mono x 109/L 1.1 1.2 1.1 1.1 1.0 0.7
    Eosin x 109/L 0.4 0.5 0.5 0.5 0.4 0.3
    Platelets (103/mm3 ) 150-350 150-350 150-350 150-350 150-350 150-350

    Coagulation profile - preterm infants (by age)

    Value
    Day 1
    Day 5
    Day 30
    PT (sec) 13 (10.6-16.2) 12.5 (10-15.3) 11.8 (10-13.6)
    APTT (sec) 53.6 (27-79) 50.5 (27-74) 44.7 (27-62)
    FBG (g/L) 2.43 (1.5-3.7) 2.8 (1.6-4.2) 2.54 (1.5-4.14)

    CSF - term and preterm infants (by age of life)

    Value
    Term < 7d
    Term > 7d
    Preterm < 7d
    Preterm > 7d
    WCC (mm3) 5 (0-30) 3 (0-10) 9 (0-30) 12 (2-70)
    RCC (mm3) 9 (0-50) <10 30 (0-333) 30
    Protein (g/L) 0.6 (0.3-2.5) 0.5 (0.2-0.8) 1 (0.5-2.9) 0.9 (0.5-2.6)
    Glucose (millimol/L) 3 (1.5-5.5) 3 (1.5-5.5) 3 (1.5-5.5) 3 (1.5-5.5)

    Urine - term and preterm infants

    Value
    Term < 7d
    Term > 7d
    Preterm < 7d
    Preterm > 7d
    WCC (per HPF) <5 <5 <5 <5
    RCC (per HPF) 0-2 0-2 0-2 0-2
    Squames (per HPF) <5 <5 <5 <5
    Organisms Nil Nil Nil Nil

    More information

    References

    • Rennie JM, Roberton NRC (Eds). Textbook of Neonatology, 3rd edn. Churchill Livingstone, Edinburgh, 1999.
    • Taeusch HW, Ballard RA (Eds). Averys Diseases of the Newborn 7th edn. W.B. Saunders Company, Philadelphia. 1998

    Other reading

    • Forfar JO. Normal and abnormal calcium, phosphorus and magnesium metabolism in the perinatal period. Clinics in Endocrinol and Metab 1976;5:123-48
    • Kuhne T, Imbach P. Neonatal platelet physiology and pathophysiology. Eur J Pediatr 1998;157:87-94
    • Hajjar FM. Neutrophils in the newborn: Normal characteristics and quantitative disorders. Sem Perinatol 1990;14:374-83
    • Strozik KS, Pieper CH, Roller J. Capillary filling time in newborn babies: normal values. Arch Dis Child 1997;76:F193-6
    • Buchanan G. Neonatal coagulation: Normal physiology and pathophysiology. Clin Haematol 1978;7:85-109

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    Safer Care Victoria

    Version history

    First published: September 2013

    Last reviewed: October 2018

    Review by: TBC

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    Page last updated: 02 Feb 2023

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