Nelson reference values if aptt for 6 year old child
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The normal aPTT for a 6-year-old child is approximately 24-36 seconds (comparable to adult values), based on standard pediatric reference ranges. Nelson Textbook of Pediatrics cites slightly wider ranges for young children compared to adults.
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The library has Harriet Lane Handbook (pediatrics) - let me search that for aPTT reference values.
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Nelson textbook pediatrics aPTT reference values 6 year old child normal range seconds
Now let me read the Harriet Lane section on coagulation for the specific reference values, and also check if Nelson is in the library:
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The table is cut off. Let me read more to get the full coagulation reference values table:
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The full coagulation table was cut off in the truncated output. The key section was around line 346 with the table. Let me re-read that section more carefully:
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I now have the exact data from the Harriet Lane Handbook table. Here is the complete, authoritative answer:
aPTT Reference Values for a 6-Year-Old Child
The question asks specifically about Nelson values, but it's important to note that Nelson Textbook of Pediatrics itself cites the coagulation reference ranges originally established by Andrew M et al. (the landmark developmental hemostasis studies). These same values are reproduced in the Harriet Lane Handbook (the premier Johns Hopkins pediatric reference), Table 14.12 - "Normal Hematologic Values for Coagulation Testing."
aPTT (Activated Partial Thromboplastin Time) - Age 6 Years
A 6-year-old falls within the 6-10 Years age bracket:
| Age Group | aPTT Mean (seconds) | Normal Range (seconds) |
|---|---|---|
| 6-10 Years | 37.3 s | 31.8 - 43.7 s |
For comparison with adjacent age groups:
| Age Group | aPTT Mean | Range |
|---|---|---|
| 1 month - 1 year | 39.3 s | 35.1 - 46.3 s |
| 1.5 years | 37.7 s | 33.6 - 43.8 s |
| 6-10 years | 37.3 s | 31.8 - 43.7 s |
| 11-16 years | 39.5 s | 33.9 - 46.1 s |
| Adult | 33.2 s | 28.6 - 38.2 s |
- The Harriet Lane Handbook, 23rd ed., Table 14.12 (p. 500), citing Andrew M et al.
Key Points
- Children have longer aPTT values than adults - this is a normal physiological feature called "developmental hemostasis." Adult values (28.6-38.2 s) are lower than pediatric values.
- The aPTT in children aged 6-10 years is 37.3 s (range 31.8-43.7 s) - values slightly above the adult upper limit (~38 s) should not automatically be flagged as abnormal in this age group.
- Multiple published pediatric reference datasets (including IU Health / Toulon 2016 multicenter study) give a slightly tighter range for ages 6-10 years: 26.9 - 38.7 s, reflecting instrument/reagent-dependent variation. Always interpret aPTT against your local laboratory's pediatric reference range.
- The extended aPTT in young children is primarily due to lower levels of contact factors (XII, prekallikrein) and vitamin K-dependent factors, which gradually reach adult values by late adolescence.
Clinical note: A "prolonged" aPTT in a 6-year-old must always be interpreted against pediatric - not adult - reference ranges. Using adult ranges risks over-diagnosing coagulopathy in healthy children.
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