Accurate measurement of HVA and 5HIAA is easily obtained in all the systems described, but, MHPG is present in relatively small concentrations in CSF, and separation from other compounds can be challenging.
As well as the measurement of HVA, 5HIAA, and MHPG, there are occasions when other metabolite analysis may become important.
This system does not allow detection of MHPG, but in most instances where MHPG concentrations might be low, specific measurement of this compound is not required, as changes in HVA concentration are always also observed.
Values for MHPG do not vary substantially with increased CSF volume drawn, so they presumably reflect spinal cord concentrations rather than those within the brain (19)
Correlated reductions in cerebrospinal fluid 5-HIAA and MHPG concentrations after treatment with selective serotonin reuptake inhibitors.
Nonstandard abbreviations: CNS, central nervous system; CSF, cerebrospinal fluid; HVA, homovanillic acid; 5HIAA, 5-hydroxyindoleacetic acid; MHPG, 3-methoxy, 4-hydroxyphenylglycol; BH4, tetrahydrobiopterin; PLP, pyridoxal 5'-phosphate; AADC, aromatic L-amino acid decarboxylase; PNPO, pyridox(am)ine phosphate oxidase; EC, electrochemical.
Although scientists do not know the exact proportion of urinary MHPG that derives from the brain, Samson and her coworkers note that animal studies have shown a strong link between learned helplessness and higher brain levels of the substance.
Depressed patients with greater amounts of urinary MHPG often prove less likely to benefit from antidepressant drugs, they add.
4], tetrahydrobiopterin; THD, tyrosine hydroxylase deficiency; CSF, cerebrospinal fluid; 5-HIAA, 5-hydroxyindoleacetic acid; HVA, homovanillic acid; MHPG
, 3-methoxy-4-hydroxy-phenylglycol; and VMA, vanillylmandelic acid.
As we look forward to continuing our improvement efforts, we expect that HMO Blue, a relatively young plan, and Bay State Health Care, a plan integrated into Blue Cross and Blue Shield just two years ago, will both demonstrate better than average performance in future MHPG analyses.
Blue Cross and Blue Shield of Massachusetts is actively participating in three major projects designed to develop and report clinical quality measurements: MHPG, the New England HEDIS Coalition and the national NCQA HEDIS Pilot Report Card, whose results were released last week.