Intensified Rates of Venous Sampling Unmask the Presence of Spontaneous, High-Frequency Pulsations of Luteinizing Hormone in Man*

Abstract

To test the validity of venous sampling rates that are generally used to characterize pulsatile LH release in man (e.g. sampling every 15-20 min), we characterized apparent LH pulse frequency in blood withdrawn variously at 20- or 4-min intervals in 19 men, at 2-min intervals in 14 men, and at 1-min intervals in 6 men. In an effort to minimize detection bias, significant LH pulses were evaluated objectively using a computerized pulse-detection algorithm, which tended to maximize recognition of true-positive LH pulses, and minimize false-positive and false-negative pulses. Under these conditions, intensified rates of venous sampling at 4-, 2-, and 1-min intervals exposed approximately 3.6, 4.9, and 13.7-fold more LH pulses, respectively, than could be discerned at a 20-min sampling frequency. In addition, more rapid rates of venous sampling disclosed a previously unobserved pattern of LH pulses, in which higher frequency, lower amplitude LH pulsations were interposed among low frequency, high amplitude LH peaks. Quantitatively, LH pulses unmasked by intensified rates of venous sampling exhibited significantly lower pulse amplitudes, expressed either as a fractional (%) or absolute (mIU/ml) increment, than pulses identified at 20-min intervals. In conclusion, we demonstrated that intensified rates of venous sampling unmask a significant number of otherwise unrecognized LH pulses in the circulation of normal men. Moreover, because generally employed sampling rates overlooked these more rapid physiological fluctuations in LH concentrations, patterns of both high and low frequency LH pulsations must now be characterized in various states of health and disease using more rapid sampling paradigms.

Ultradian Oscillations of Insulin Secretion in Humans

“…Spectral analysis of the deconvoluted ISR profiles confirmed the presence of two significant rhythmic components: one with a mean periodicity of 48 -96 min, the other with a mean periodicity of 6 -12 min. Altogether, these results indicate that the temporal organization of insulin secretion is analogous to that of luteinizing hormone or growth hormone, for which the presence of both rapid and slow secretory pulses has been demonstrated (20,21). Relationship with sleep and sympathovagal activity.…”

Relationships of thyroid hormones, IGF-I and testosterone in breeds of ram lambs with low and high prolificacies

“…In the routine IGF-I assay using commercial kits, a final dilution of 1:100 is required; therefore, any error in the pipetting could generate dramatic fluctuations in the final results, which may look like a pulse. To eliminate the error of the assay, and the so-called fluctuations resulting from this, the method of Veldhuis et al (1984) was used in our pulse analysis. Merriam and Wachter (1982) suggested using the moving average procedure in the analysis, of the data to reduce noise, but this method was not used in our data analysis because it reduces the sensitivity of the analysis.…”

“…Week 22 was near the beginning of the pubertal period as manifested by a prominent increase in the testosterone concentration in most of the lambs, and week 28 was the time during which IGF-I reached a plateau in the two groups. Pulses of testosterone and IGF-I were calculated according to the method described by Veldhuis et al (1984). Veldhuis et al (1984) modified the algorithm used by Merriam and Wachter (1982) and based their detection of pulses on the measurements of the hormone that exceeded the preceding local nadir by a value that was four-fold greater than the intra-assay CV of the RIA.…”

“…Pulses of testosterone and IGF-I were calculated according to the method described by Veldhuis et al (1984). Veldhuis et al (1984) modified the algorithm used by Merriam and Wachter (1982) and based their detection of pulses on the measurements of the hormone that exceeded the preceding local nadir by a value that was four-fold greater than the intra-assay CV of the RIA. This method eliminates noise produced by the error of the experiment and produces fewer false positive pulses than do other methods.…”

Novel modalities for appraising individual and coordinate pulsatile hormone secretion: the paradigm of luteinizing hormone and testosterone release in the aging male

“…6 Consequently, attempts to understand any one hormone output considered alone, pling can substantially underestimate the frequency and amplitude of pulsatile activity in neurohormone eg LH, are confounded by artificial isolation of that node within a complex highly interactive servocontrol axes. [17][18][19][20][21][22] Early observations applied to LH and growth hormone (GH) release demonstrated that sampling at system. 7 In addition, a finite number of blood or other fluid samples can be obtained in clinical and animal intervals of more than 3-5 samples per hormone burst duration and half-life over at least 24 h was required experimentation, thus commonly producing short and relatively noisy (containing significant experimental to identify the majority of evident pulsatile neuroendocrine activity in the data and capture nyctohemeral uncertainty) data series that are less tractable analytically.…”