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==Overview==
==Overview==
An immediate investigation should be started in severe [[short stature]] defined as a short child more than 3 [[standard deviation]]<nowiki/>s below the mean of children at the same age. Measurement of a random serum [[Growth hormone|GH]] level alone is not helpful. Measurement of [[Insulin-like growth factor 1|Insulin-like growth factor I]] (IGF-I) and [[Insulin-like growth factor binding protein 3|Insulin-like growth factor binding protein-3]] ([[IGFBP3|IGFBP-3]]) is more helpful than GH level alone. GH stimulation tests are indicated for most patients suspected to have GHD. If the clinical and other laboratory criteria are sufficient to make the diagnosis of GHD, there is no need to perform the test. Pharmacologic stimuli include [[clonidine]], [[glucagon]], [[arginine]], and [[insulin]]-induced [[hypoglycemia]]. Administration of [[sex steroids]] for a few days prior to the provocative [[Growth hormone|GH]] testing reduces the chance of a [[false-positive]] result.
==Laboratory Findings==
==Laboratory Findings==
GH secretion is pulsatile and its secretion is regulated by two hypothalamic factors; growth hormone releasing hormone and somatostatin. [33]


So, measurement of a random serum GH level alone is not helpful and usually other tests used with it:
=== Neonatal evaluation ===
* insulin-like growth factor I (IGF-I)
* Always measure GH levels:
* insulin-like growth factor binding protein-3 (IGFBP-3) levels is the major serum carrier protein for IGF-I [45-47] and the most GH dependent [48].
**In the presence of neonatal hypoglycemia
Their concentrations often reflect the integrated concentration of secreted GH.[35-38],
**In the absence of a metabolic disorder.
**A random GH measurement in a polyclonal RIA of less than 20 mg/L would suggest GHD within the newborn.
**An IGFBP-3 measurement is of value for the diagnosis of GHD in infancy.


They are better tests than GH level because they are stable during the day and not pulsatile. [34]
=== Children evaluation ===
The evaluation for GHD in a short child can not be initiated until exclusion of other causes of growth failure, which include hypothyroidism, chronic systemic disease, and Turner syndrome.


Limitations
Indications for immediate investigation include:
* Severe [[short stature|short stature:]] a short child more than 3 [[Standard deviation|standard deviations]] (SD) below the mean height of children of the same age
* In the absence of [[short stature]]: a height velocity more than 2 SD below the mean height for more than 1 year or more than 1.5 SD sustained over 2 years
* Height more than 1.5 SD below the mid-parental height
* Height more than 2 SD below the mean height and a height velocity of 1 or more SD below the [[mean]] height for chronological age sustained for more than a year
* A decrease in height SD of more than 0.5 over 1 year in children over 2 years of age
* Signs indicative of an [[Intracranial mass|intracranial lesion]]
=== Adult evaluation ===
Indications for immediate investigation include:
* Adults with known [[hypothalamic]] or [[pituitary disease]] such as:
**[[Panhypopituitarism]] with documented deficiency of [[thyroid-stimulating hormone]] (TSH), [[corticotropin]] (ACTH), and [[Gonadotropins|gonadotropins.]] 
**Multiple deficiencies of other pituitary hormones correlated highly with a subnormal GH response to a stimulation test.<ref>{{Cite journal


Serum IGF-I levels may be low in conditions other than GHD, such as growth hormone insensitivity (GHI), hypothyroidism [41], diabetes [42], renal failure [41,43], and cancer [44].
| author = [[Mark L. Hartman]], [[Brenda J. Crowe]], [[Beverly M. K. Biller]], [[Ken K. Y. Ho]], [[David R. Clemmons]] & [[John J. Chipman]]
| title = Which patients do not require a GH stimulation test for the diagnosis of adult GH deficiency?
| journal = [[The Journal of clinical endocrinology and metabolism]]
| volume = 87
| issue = 2
| pages = 477–485
| year = 2002
| month = February
| doi = 10.1210/jcem.87.2.8216
| pmid = 11836272
}}</ref>
**A low serum [[Insulin-like growth factor-I|IGF-1]] concentration confirms the diagnosis of GH deficiency in these patients; provocative testing is not required.<ref>{{Cite journal


Interpretation
| author = [[Maria Fleseriu]], [[Ibrahim A. Hashim]], [[Niki Karavitaki]], [[Shlomo Melmed]], [[M. Hassan Murad]], [[Roberto Salvatori]] & [[Mary H. Samuels]]
| title = Hormonal Replacement in Hypopituitarism in Adults: An Endocrine Society Clinical Practice Guideline
| journal = [[The Journal of clinical endocrinology and metabolism]]
| volume = 101
| issue = 11
| pages = 3888–3921
| year = 2016
| month = November
| doi = 10.1210/jc.2016-2118
| pmid = 27736313
}}</ref>
* Adults with a history of GH deficiency in childhood. Some will be found to have normal [[Growth hormone|GH]] secretion as adults, although patients with GH deficiency due to an organic cause such as [[pituitary adenoma]] never show normal [[Growth hormone|GH]] level.


●'''Moderately or severely reduced''' IGF-I and IGFBP-3 '''with''' delayed bone age:
=== What to measure ===
GH secretion is pulsatile and its secretion is regulated by way of  hypothalamic factors; growth hormone releasing hormone (GHRH) and somatostatin.<ref name="pmid20161791">{{cite journal| author=Osterstock G, Escobar P, Mitutsova V, Gouty-Colomer LA, Fontanaud P, Molino F et al.| title=Ghrelin stimulation of growth hormone-releasing hormone neurons is direct in the arcuate nucleus. | journal=PLoS One | year= 2010 | volume= 5 | issue= 2 | pages= e9159 | pmid=20161791 | doi=10.1371/journal.pone.0009159 | pmc=2820089 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20161791  }}</ref> Measurement of a random serum GH level alone isn't always beneficial, other tests which can be used in the diagnosis include:
* [[Insulin-like growth factor 1|Insulin-like growth factor I]] (IGF-I)
* [[Insulin-like growth factor binding protein 3|Insulin-like growth factor binding protein-3]] ([[IGFBP3|IGFBP-3]]) levels: it is the major serum carrier protein for [[Insulin-like growth factor-I|IGF-I]] and the most [[Growth hormone|GH]] dependent.<ref name="pmid2431001">{{cite journal| author=Baxter RC, Martin JL| title=Radioimmunoassay of growth hormone-dependent insulinlike growth factor binding protein in human plasma. | journal=J Clin Invest | year= 1986 | volume= 78 | issue= 6 | pages= 1504-12 | pmid=2431001 | doi=10.1172/JCI112742 | pmc=423906 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2431001  }}</ref>


•In most cases, the possibility of GHD should be explored by provocative GH testing, if other causes of low IGF-1 and IGFBP-3, such as poor nutrition, have been excluded.  
==== Limitations ====
* Serum [[Insulin-like growth factor-I|IGF-I]] levels may be low in other conditions such as [[Growth hormone insensitivity syndrome|growth hormone insensitivity]], [[hypothyroidism]], [[renal failure]], [[Diabetes mellitus|diabetes]], and [[cancer]].<ref name="pmid3760118">{{cite journal| author=Powell DR, Rosenfeld RG, Baker BK, Liu F, Hintz RL| title=Serum somatomedin levels in adults with chronic renal failure: the importance of measuring insulin-like growth factor I (IGF-I) and IGF-II in acid-chromatographed uremic serum. | journal=J Clin Endocrinol Metab | year= 1986 | volume= 63 | issue= 5 | pages= 1186-92 | pmid=3760118 | doi=10.1210/jcem-63-5-1186 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=3760118  }}</ref>


•If the growth failure is severe, bone age is significantly delayed, and IGF-I and IGFBP-3 are definitively low (eg, <-2 SD), it is reasonable to make the diagnosis of GHD without performing GH stimulation testing, especially in the setting of known hypothalamic-pituitary disease and/or its treatment (eg, brain surgery and/or radiation)
==== Interpretation ====
* Reduced level of [[Insulin-like growth factor-I|IGF-I]] and [[IGFBP3|IGFBP-3]] with [[Bone age|delayed bone age]]: provocative [[Growth hormone|GH]] testing is needed. If the growth failure is severe and [[Insulin-like growth factor-I|IGF-I]] and [[IGFBP3|IGFBP-3]] are severely low, there is no need to perform [[Growth hormone|GH]] stimulation testing.


●'''Clearly normal''' IGF-1 and IGFBP-3 (SD ≥0); ie, in the upper half of the normal range) – GHD is extremely unlikely, and no further testing is required.
* Normal [[Insulin-like growth factor-I|IGF-1]] and [[IGFBP3|IGFBP-3]]: no further testing is required.


'''GH stimulation tests'''
=== '''GH stimulation tests''' ===
* It is indicated for most patients suspected to have GHD.
* The results should be interpreted in the context of [[bone age]], [[Insulin-like growth factor-I|IGF-1]] and [[IGFBP3|IGFBP-3]] concentrations.


Indications
* If the clinical and other laboratory criteria are sufficient to make the diagnosis of GHD, there is no need to perform the test. 


most patients to confirm a diagnosis of GHD. Because this testing has limitations, the results should not be used as the sole diagnostic criterion, and should be interpreted in the context of auxological findings, bone age, and IGF-1 and IGFBP-3 concentrations.
* A serum GH concentration of >10 mcg/L with a cutoff of 7.5 mcg/L is often used for modern assays.


Provocative GH testing is '''not''' necessary for selected patients in whom other clinical criteria are sufficient to make the diagnosis of GHD, including those with the following conditions: 
* The stimulation tests are performed after an overnight fast. Serum samples are collected at intervals to capture the peak [[Growth hormone|GH]] level.


●Pituitary abnormality (secondary to a congenital anomaly, tumor, or irradiation), and a known deficiency of at least one other pituitary hormone, as well as auxological criteria [51].
* Two different stimuli should be used for most patients.<ref name="pmid27884013">{{cite journal| author=Grimberg A, DiVall SA, Polychronakos C, Allen DB, Cohen LE, Quintos JB et al.| title=Guidelines for Growth Hormone and Insulin-Like Growth Factor-I Treatment in Children and Adolescents: Growth Hormone Deficiency, Idiopathic Short Stature, and Primary Insulin-Like Growth Factor-I Deficiency. | journal=Horm Res Paediatr | year= 2016 | volume= 86 | issue= 6 | pages= 361-397 | pmid=27884013 | doi=10.1159/000452150 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27884013  }}</ref>
* In a patient with other [[pituitary hormone]] defects or a [[Genetics|genetic]] defect, one test is sufficient to establish the diagnosis.<ref name="pmid18425584">{{cite journal| author=Richmond EJ, Rogol AD| title=Growth hormone deficiency in children. | journal=Pituitary | year= 2008 | volume= 11 | issue= 2 | pages= 115-20 | pmid=18425584 | doi=10.1007/s11102-008-0105-7 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18425584  }}</ref>
* Pharmacologic stimuli include [[clonidine]], [[glucagon]], [[arginine]], and [[insulin]]-induced [[hypoglycemia]]:<ref name="pmid169508">{{cite journal| author=| title=Stimulation of growth hormone secretion by levodopa-propranolol in children and adolescents. | journal=Pediatrics | year= 1975 | volume= 56 | issue= 2 | pages= 262-6 | pmid=169508 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=169508  }}</ref>
{| class="wikitable"
!Test
!Mechanism
!Dose
!Peak of effect
!Side effect
|-
|[[Clonidine]] 
|stimulation of [[Growth hormone-releasing hormone|GHRH]] via [[Alpha-adrenergic receptor|alpha-adrenergic]] pathways<ref>{{Cite journal


●Newborn with a congenital pituitary abnormality (ectopic posterior pituitary and pituitary hypoplasia with abnormal stalk) or known deficiency of a pituitary hormone, along with hypoglycemia, at which time a simultaneous serum GH concentration is <5 mcg/L [51].
| author = [[N. C. Fraser]], [[J. Seth]] & [[N. S. Brown]]
| title = Clonidine is a better test for growth hormone deficiency than insulin hypoglycaemia
| journal = [[Archives of disease in childhood]]
| volume = 58
| issue = 5
| pages = 355–358
| year = 1983
| month = May
| pmid = 6344804
}}</ref>
|5 mcg/kg 
|One hour
|[[Hypotension]] and hypoglycemia<ref>{{Cite journal


●Infant or young child with extreme short stature (eg, height <-3 SD), normal nutrition, significantly reduced IGF-I (eg, <-2 SD) and IGFBP-3 and delayed bone age. This is the classic presentation of congenital and severe GHD, and most experts agree that provocative testing is not required to make the diagnosis. 
| author = [[Monika Obara-Moszynska]], [[Andrzej Kedzia]], [[Eugeniusz Korman]] & [[Marek Niedziela]]
| title = Usefulness of growth hormone (GH) stimulation tests and IGF-I concentration measurement in GH deficiency diagnosis
| journal = [[Journal of pediatric endocrinology & metabolism : JPEM]]
| volume = 21
| issue = 6
| pages = 569–579
| year = 2008
| month = June
| pmid = 18717243
}}</ref>   
|-
|[[Arginine]]
|Stimulates [[Growth hormone|GH]] release
|0.5 g/kg 
|One hour
|No side effects 
|-
|[[Glucagon]]<ref>{{Cite journal


a serum GH concentration of >10 mcg/L, but a cutoff of 7.5 mcg/L is often used for modern assays.  
| author = [[K. S. Leong]], [[A. B. Walker]], [[I. Martin]], [[D. Wile]], [[J. Wilding]] & [[I. A. MacFarlane]]
* The stimulation tests are performed after an overnight fast. After the pharmacologic stimulus, serum samples are collected at intervals designed to capture the peak GH level; the expected time to this peak varies with the stimulus administered.
| title = An audit of 500 subcutaneous glucagon stimulation tests to assess growth hormone and ACTH secretion in patients with hypothalamic-pituitary disease
| journal = [[Clinical endocrinology]]
| volume = 54
| issue = 4
| pages = 463–468
| year = 2001
| month = April
| pmid = 11318781
}}</ref> 
|Transient [[hyperglycemia]]
|0.03 mg/kg 
|Three hours 
|[[Nausea]], [[vomiting]], [[sweating]], and [[headache]]
|-
|[[Insulin]]<ref>{{Cite journal


* that two different stimuli should be used for most patients [51].
| title = Consensus guidelines for the diagnosis and treatment of growth hormone (GH) deficiency in childhood and adolescence: summary statement of the GH Research Society. GH Research Society
* In a patient with a known pathology of the central nervous system, other pituitary hormone defects, or a genetic defect, one test is sufficient to establish the diagnosis [32,60].
| journal = [[The Journal of clinical endocrinology and metabolism]]
* Pharmacologic stimuli include clonidine [62] glucagon [63], arginine [64], and insulin-induced hypoglycemia [65-67].
| volume = 85
* Clonidine stimulates GH by several mechanisms, including the stimulation of GHRH via alpha-adrenergic pathways.
| issue = 11
* It is administered at a dose of 5 mcg/kg (maximum 250 mcg), and serum GH is measured at 0, 30, 60 and 90 minutes; peak GH secretion typically occurs about one hour after the stimulus is given [60]. Clonidine may cause modest hypotension and hypoglycemia, so patients should be monitored for these problems during the test. Estimates of this test's sensitivity and specificity vary considerably [68,69].
| pages = 3990–3993
* Arginine  [60] There are no side effects from this test
| year = 2000
* Glucagon — Administration of glucagon causes transient hyperglycemia, which in turn stimulates endogenous insulin secretion followed by controlled hypoglycemia, and consequent GH secretion [60,70].  
| month = November
* a good choice for infants and young children.
| doi = 10.1210/jcem.85.11.6984
* side effects include nausea, vomiting, sweating, or headaches.
| pmid = 11095419
* insulin-induced hypoglycemia is a potent stimulant of GH release this test is less commonly used in children because of safety concerns [32]  
}}</ref>
|Insulin-induced [[hypoglycemia]] is a potent stimulant of [[Growth hormone|GH]] release
|
|
|[[Hypoglycemia]]
|}


'''Limitations''' (table 1) [7]:
==== Interpretation ====
* The interpretation of the test results depends upon age and [[Sex hormones|sex hormone]] concentrations.
* Children with [[Constitutional growth delay|constitutional delay]] of growth and puberty may have low [[Growth hormone|GH]] results on provocative testing in the absence of true GHD.
* Administration of [[sex steroids]] for a few days prior to the provocative GH testing reduces the chance of a false-positive result.


●The interpretation of the test results depends upon age and sex hormone concentrations [52]. Children with constitutional delay of growth and puberty may have low GH results on provocative testing in the absence of true GHD (ie, false-positive results). Administration of sex steroids for a few days prior to the provocative GH testing (known as "priming") reduces the chance of a false-positive result, as discussed below.
●Adiposity (as measured by the body mass index [BMI]) also influences GH response to the stimulation test, such that obese children show diminished GH responses to all stimuli [51,53,54].
●The tests rely upon GH assays of variable accuracy.
●The tests are expensive, uncomfortable and carry some risks.
●Test reproducibility has not been adequately documented.
●The ability of the tests to discriminate between normal short children and children with partial GHD is limited.
Because of these limitations, it is clear that there is no real "gold standard" for the diagnosis of GHD [32]. Nonetheless, GH stimulation tests are a valuable diagnostic tool when combined with auxological data and measurements of IGF-1 and IGFBP-3. The peak GH response to provocative testing is also a useful predictor of response during the first year of treatment with GH [55,56].
==References==
==References==
{{Reflist|2}}
{{Reflist|2}}
{{WH}}
{{WS}}

Latest revision as of 14:08, 27 October 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohammed Abdelwahed M.D[2]

Overview

An immediate investigation should be started in severe short stature defined as a short child more than 3 standard deviations below the mean of children at the same age. Measurement of a random serum GH level alone is not helpful. Measurement of Insulin-like growth factor I (IGF-I) and Insulin-like growth factor binding protein-3 (IGFBP-3) is more helpful than GH level alone. GH stimulation tests are indicated for most patients suspected to have GHD. If the clinical and other laboratory criteria are sufficient to make the diagnosis of GHD, there is no need to perform the test. Pharmacologic stimuli include clonidine, glucagon, arginine, and insulin-induced hypoglycemia. Administration of sex steroids for a few days prior to the provocative GH testing reduces the chance of a false-positive result.

Laboratory Findings

Neonatal evaluation

  • Always measure GH levels:
    • In the presence of neonatal hypoglycemia
    • In the absence of a metabolic disorder.
    • A random GH measurement in a polyclonal RIA of less than 20 mg/L would suggest GHD within the newborn.
    • An IGFBP-3 measurement is of value for the diagnosis of GHD in infancy.

Children evaluation

The evaluation for GHD in a short child can not be initiated until exclusion of other causes of growth failure, which include hypothyroidism, chronic systemic disease, and Turner syndrome.

Indications for immediate investigation include:

  • Severe short stature: a short child more than 3 standard deviations (SD) below the mean height of children of the same age
  • In the absence of short stature: a height velocity more than 2 SD below the mean height for more than 1 year or more than 1.5 SD sustained over 2 years
  • Height more than 1.5 SD below the mid-parental height
  • Height more than 2 SD below the mean height and a height velocity of 1 or more SD below the mean height for chronological age sustained for more than a year
  • A decrease in height SD of more than 0.5 over 1 year in children over 2 years of age
  • Signs indicative of an intracranial lesion

Adult evaluation

Indications for immediate investigation include:

  • Adults with known hypothalamic or pituitary disease such as:
  • Adults with a history of GH deficiency in childhood. Some will be found to have normal GH secretion as adults, although patients with GH deficiency due to an organic cause such as pituitary adenoma never show normal GH level.

What to measure

GH secretion is pulsatile and its secretion is regulated by way of  hypothalamic factors; growth hormone releasing hormone (GHRH) and somatostatin.[3] Measurement of a random serum GH level alone isn't always beneficial, other tests which can be used in the diagnosis include:

Limitations

Interpretation

GH stimulation tests

  • It is indicated for most patients suspected to have GHD.
  • The results should be interpreted in the context of bone age, IGF-1 and IGFBP-3 concentrations.
  • If the clinical and other laboratory criteria are sufficient to make the diagnosis of GHD, there is no need to perform the test. 
  • A serum GH concentration of >10 mcg/L with a cutoff of 7.5 mcg/L is often used for modern assays.
  • The stimulation tests are performed after an overnight fast. Serum samples are collected at intervals to capture the peak GH level.
Test Mechanism Dose Peak of effect Side effect
Clonidine  stimulation of GHRH via alpha-adrenergic pathways[9] 5 mcg/kg  One hour Hypotension and hypoglycemia[10]   
Arginine Stimulates GH release 0.5 g/kg  One hour No side effects 
Glucagon[11]  Transient hyperglycemia 0.03 mg/kg  Three hours  Nausea, vomiting, sweating, and headache
Insulin[12] Insulin-induced hypoglycemia is a potent stimulant of GH release Hypoglycemia

Interpretation

  • The interpretation of the test results depends upon age and sex hormone concentrations.
  • Children with constitutional delay of growth and puberty may have low GH results on provocative testing in the absence of true GHD.
  • Administration of sex steroids for a few days prior to the provocative GH testing reduces the chance of a false-positive result.

References

  1. ↑ Mark L. Hartman, Brenda J. Crowe, Beverly M. K. Biller, Ken K. Y. Ho, David R. Clemmons & John J. Chipman (2002). "Which patients do not require a GH stimulation test for the diagnosis of adult GH deficiency?". The Journal of clinical endocrinology and metabolism. 87 (2): 477–485. doi:10.1210/jcem.87.2.8216. PMID 11836272. Unknown parameter |month= ignored (help)
  2. ↑ Maria Fleseriu, Ibrahim A. Hashim, Niki Karavitaki, Shlomo Melmed, M. Hassan Murad, Roberto Salvatori & Mary H. Samuels (2016). "Hormonal Replacement in Hypopituitarism in Adults: An Endocrine Society Clinical Practice Guideline". The Journal of clinical endocrinology and metabolism. 101 (11): 3888–3921. doi:10.1210/jc.2016-2118. PMID 27736313. Unknown parameter |month= ignored (help)
  3. ↑ Osterstock G, Escobar P, Mitutsova V, Gouty-Colomer LA, Fontanaud P, Molino F; et al. (2010). "Ghrelin stimulation of growth hormone-releasing hormone neurons is direct in the arcuate nucleus". PLoS One. 5 (2): e9159. doi:10.1371/journal.pone.0009159. PMC 2820089. PMID 20161791.
  4. ↑ Baxter RC, Martin JL (1986). "Radioimmunoassay of growth hormone-dependent insulinlike growth factor binding protein in human plasma". J Clin Invest. 78 (6): 1504–12. doi:10.1172/JCI112742. PMC 423906. PMID 2431001.
  5. ↑ Powell DR, Rosenfeld RG, Baker BK, Liu F, Hintz RL (1986). "Serum somatomedin levels in adults with chronic renal failure: the importance of measuring insulin-like growth factor I (IGF-I) and IGF-II in acid-chromatographed uremic serum". J Clin Endocrinol Metab. 63 (5): 1186–92. doi:10.1210/jcem-63-5-1186. PMID 3760118.
  6. ↑ Grimberg A, DiVall SA, Polychronakos C, Allen DB, Cohen LE, Quintos JB; et al. (2016). "Guidelines for Growth Hormone and Insulin-Like Growth Factor-I Treatment in Children and Adolescents: Growth Hormone Deficiency, Idiopathic Short Stature, and Primary Insulin-Like Growth Factor-I Deficiency". Horm Res Paediatr. 86 (6): 361–397. doi:10.1159/000452150. PMID 27884013.
  7. ↑ Richmond EJ, Rogol AD (2008). "Growth hormone deficiency in children". Pituitary. 11 (2): 115–20. doi:10.1007/s11102-008-0105-7. PMID 18425584.
  8. ↑ "Stimulation of growth hormone secretion by levodopa-propranolol in children and adolescents". Pediatrics. 56 (2): 262–6. 1975. PMID 169508.
  9. ↑ N. C. Fraser, J. Seth & N. S. Brown (1983). "Clonidine is a better test for growth hormone deficiency than insulin hypoglycaemia". Archives of disease in childhood. 58 (5): 355–358. PMID 6344804. Unknown parameter |month= ignored (help)
  10. ↑ Monika Obara-Moszynska, Andrzej Kedzia, Eugeniusz Korman & Marek Niedziela (2008). "Usefulness of growth hormone (GH) stimulation tests and IGF-I concentration measurement in GH deficiency diagnosis". Journal of pediatric endocrinology & metabolism : JPEM. 21 (6): 569–579. PMID 18717243. Unknown parameter |month= ignored (help)
  11. ↑ K. S. Leong, A. B. Walker, I. Martin, D. Wile, J. Wilding & I. A. MacFarlane (2001). "An audit of 500 subcutaneous glucagon stimulation tests to assess growth hormone and ACTH secretion in patients with hypothalamic-pituitary disease". Clinical endocrinology. 54 (4): 463–468. PMID 11318781. Unknown parameter |month= ignored (help)
  12. ↑ "Consensus guidelines for the diagnosis and treatment of growth hormone (GH) deficiency in childhood and adolescence: summary statement of the GH Research Society. GH Research Society". The Journal of clinical endocrinology and metabolism. 85 (11): 3990–3993. 2000. doi:10.1210/jcem.85.11.6984. PMID 11095419. Unknown parameter |month= ignored (help)
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