Assays for GH, IGF-I, and IGF binding protein-3

Optimal timing of blood samplings to detect GH inhibition during oral glucose tolerance test

BACKGROUND

In patients with suspected acromegaly, evaluation of IGF-I is recommended as first-line test, while the assessment of GH-nadir during oral glucose tolerance test (OGTT) is advised as confirmatory test. The procedure of this test generally involves GH measurement every 30 min (30') from baseline to +120' or +180'. However, the optimal timing of samplings for the distinction between patients with or without active acromegaly is still a matter of debate.

METHODS

Sixty-seven healthy subjects and 46 acromegalic patients who achieved documented and persistent long-term cure were enrolled. A greedy algorithm was used to identify the minimal subset of time-points that sufficed to correctly detect GH suppression.

RESULTS

The sampling at 90' was the one in which a GH level < 1 μg/L was most frequently achieved (i.e., in 91.3% of cured acromegalic patients and in 91.0% of healthy subjects). Considering the whole cohort, the best combination of 2 time-points was +90' and +150' and achieved 95.6% accuracy; the best combination of 3 time-points was +60', +90' and +150' and achieved 99.1% accuracy. The minimal subset of GH determinations that demonstrated perfect accuracy (100%) needed the inclusion of 4 time-points, namely +60', +90', +120' and +150'.

CONCLUSION

A subset of 4 time-points (60' - 90' - 120' - 150') was identified as the most relevant to detect GH suppression at OGTT, with a perfect classification of 100% of subjects. This supports the possibility to restrict the blood samplings to these time-points when assessing disease cure, with possible advantages in terms of saving time and lowering costs.

Lower albumin levels are associated with frailty measures, trace elements, and an inflammation marker in a cross-sectional study in Tanushimaru

Background

There is little data on the association between the lower nutrition represented by serum albumin levels and related factors in a general population. The present study aimed to determine whether the albumin level positioned as some kind of biomarker with frailty measures, trace elements, and an inflammation marker.

Methods

In 2018, we performed an epidemiological survey in 1368 subjects who resided in Tanushimaru, Japan, in which we examined the blood chemistry including albumin, trace elements, hormone levels, and carotid ultrasonography. Albumin levels were categorized into 4 groups (G1 [3.2–3.9 mg/dL], G2 [4.0–4.3 mg/dL], G3 [4.4–4.6 mg/dL], and G4 [4.7–5.3 mg/dL]). The participants underwent measurements of handgrip strength and were tested by asking to walk 5 m. Their cognitive functions were evaluated by the mini-mental state examination (MMSE).

Results

Multiple stepwise regression analysis demonstrated that albumin levels were significantly and independently associated with age (inversely), systolic blood pressures, estimated glomerular filtration rate (eGFR), MMSE score, frailty measures (handgrip strength), an inflammation marker (high-sensitivity C-reactive protein), hormones (growth hormone (inversely) and insulin-like growth factor-1), and trace elements (calcium, magnesium, iron, and zinc), with a linear trend.

Conclusions

Lower albumin levels, even in the normal range, were found to be related factors of frailty measures, trace elements, and an inflammation marker in a general population.