Method and device for diagnosing and treating insulin-like growth factor deficiency disorders
The present invention provides standard deviation score (SDS) calculators, which SDS calculators are useful for transforming insulin-like growth factor-1 (IGF-1) concentrations to IGF-1 standard deviation scores. In one embodiment, IGF-1 blood levels are calculated so as to take into account IGFBP-3 blood levels (and, optionally, IGF-2 blood levels) to provide an IGF-1 production rate, which can be used to calculate an IGF-1 production rate SDS. The IGF-1 SDS and IGF-1 production rate SDS are particularly useful in assessing the stimulated rate of IGF-1 production in response to, for example, growth hormone therapy.
1. A method of treating an insulin-like growth factor-1 deficiency (IGFD) disorder in an individual, the method comprising:
a) calculating an insulin-like growth factor-1 (IGF-1) clearance rate using an IGF-1 binding protein-3 (IGFBP3) concentration measured in a blood, plasma, or serum sample from the individual;
b) determining an IGF-1 production rate, wherein the IGF-1 production rate is calculated using a computer program that, when read by a computer, executes calculation of an IGF-1 production rate, wherein the IGF-1 production rate is calculated using the algorithm:
IGF-1 production rate =(IGF-1 blood conc. )(clearance rate of IGF-1),
wherein said IGF-1 blood conc is an IGF-1 concentration measured in a blood, plasma, or serum sample from the individual; and
c) administering to the individual, based on the determined IGF-1 production rate, an effective amount of IGF 1 or growth hormone (GH), or an effective amount of a combination of GH and IGF-1, said administering being effective to treat IGFD in the individual.
2. The method of claim 1 , further comprises transforming the IGF-1 production rate to an IGF-1 production rate standard deviation score (IGF-1 PR SDS); wherein the IGF-1 PR SDS is calculated using the algorithm
IGF-1 PR SDS=( x p −mean age )÷SD age ,
wherein x is the IGF-1 production rate in blood, wherein the standard deviation score is an IGF-1 production rate standard deviation score (IGF-1 PR SDS), which IGF-1 PR SDS is based on an IGF-1 production rate calculated from the IGF-1 blood concentration in the biological sample from the individual.
3. The method of claim 1 , wherein said administering comprises administering to the individual a combination of GH and IGF-1.
4. The method of claim 1 , wherein the IGFD disorder is short stature.
5. The method of claim 1 , wherein the IGFD disorder is a metabolic disorder.
6. The method of claim 1 , wherein said IGF-1 production rate in blood is adjusted for a blood concentration of insulin-like growth factor-2 (IGF-2).
7. The method of claim 2 , wherein said determining step further comprises:
i) determining an IGF-1 production rate in blood at baseline to provide a first IGF-1 PR SDS,
ii) computing IGF-1 production rate in response to growth hormone (GH) administration to provide a second IGF-1 PR SDS; and
iii) computing a change in IGF-1 PR SDS between said first and second IGF-1 PR SDS.
8. The method of claim 1 , wherein the IGF-1 is recombinant human IGF-1.
9. The method of claim 1 , wherein the GH is recombinant human GH.