Special Feature

Prehypertension: Is It Relevant for Nephrologists?

Norman M. Kaplan Department of Internal Medicine, Division of , University of Texas Southwestern Medical School, Dallas, Texas

Prehypertension has been proposed as the diagnosis for the presence of blood pressures >120/80 mmHg but <140/90 mmHg. It covers more than 60 million people in the United States and nephrologists will increasingly be involved with them. This review describes its relevance to nephrologists. Clin J Am Soc Nephrol 4: 1381–1383, 2009. doi: 10.2215/CJN.02340409

ephrologists will rarely deal with patients who have experienced a two-fold increase in death from cardiovascular prehypertension (i.e., BP below hypertension [140/90 . mmHg] but above ideal [120/80 mmHg]), which In addition to these mortality data, a number of studies of NϾ includes 60 million people in the United States (1). Because smaller populations have shown an increase in nonfatal target there are hardly enough nephrologists to care for the increasing organ damage (3). For the sake of brevity, emphasis is placed number of patients with chronic kidney , why should on those that relate to the kidneys: they be concerned about patients who do not yet have hyper- • Left ventricular hypertrophy (4) tension? • Coronary calcification (5) The reasons include the following: First, multiple data show • Reduced coronary flow reserve (6) that people with prehypertension often have subclinical target • Progression of coronary atherosclerosis (7) organ damage, including nephropathy. Second, the families of • Increases in ischemic coronary disease and (8) patients with chronic kidney disease (CKD) harbor an in- • Poor cognitive function (9) creased prevalence of nephropathy, and they need early recog- • Retinal vascular changes (10) nition. Third, if recognized, then it may be possible to reverse • Elevated serum uric acid (11) the usual progression into overt hypertension and thereby pre- vent patients from developing hypertension-related organ Albuminuria in levels even below the level that defines mi- damage. croalbuminuria is predictive of both hypertension (12) and cardiovascular morbidity and mortality, independent of renal Evidence of Subclinical Target Organ function, hypertension, or (13). Patients with prehy- Damage pertension have an increased prevalence of microalbuminuria During the past 10 yrs, a large body of evidence has shown (14). In this study of almost 2700 patients, those with prehy- the risks of prehypertensive levels of BP. Perhaps the most pertension had a prevalence of microalbuminuria of 4.9%, com- convincing are the data from the Prospective Studies Collabo- pared with a prevalence of 2.8% in those with normal BP. ration, which followed almost 1 million people with no previ- Similar associations have been reported from other populations ous vascular disease prospectively for a total of 12.7 million (15). Of additional interest, serum uric acid, believed by some to person-years in 61 observational studies (2) and examined the be a major determinant of hypertension and atherosclerosis, is relationship between levels of BP and subsequent mortality. associated with microalbuminuria in individuals with prehy- The data show a continuous increase in mortality from both pertension (16). stroke and ischemic heart disease from 115/75 mmHg, the lowest level with a large enough group that could be followed. Predictors of Prehypertension In those with a 20-mmHg higher systolic BP or a 10-mmHg Because prehypertension is one step toward hypertension, higher diastolic BP, mortality rates doubled; therefore, patients the same factors are involved in the development of both. with BP of 135/85, well within the range of prehypertension, Obesity is foremost, with male gender and black race also involved (17). In addition, these factors are associated with more prehypertension: Diabetes, impaired glucose tolerance,

Received April 8, 2009. Accepted May 26, 2009. the metabolic syndrome, dyslipidemia, and smoking (18). Perhaps the main reason that nephrologists should consider Published online ahead of print. Publication date available at www.cjasn.org. prehypertension is their opportunity to identify many of those Correspondence: Dr. Norman M. Kaplan, Department of Internal Medicine, who are most likely to develop it: The families of their patients Division of Hypertension, University of Texas Southwestern Medical School, 5323 Harry Hines Boulevard, Dallas, TX 75390-8586. Phone: 214-648-2103; Fax: 214- with CKD or ESRD. As shown in the Kidney Evaluation and 648-3063; E-mail: [email protected] Awareness Program in Sheffield (KEAPS) trial, relatives of

Copyright © 2009 by the American Society of Nephrology ISSN: 1555-9041/408–1381 1382 Clinical Journal of the American Society of Nephrology Clin J Am Soc Nephrol 4: 1381–1383, 2009 patients with CKD were six times more likely to have mi- 9. Knecht S, Wersching H, Lohmann H, Bruchmann M, Dun- croalbuminuria than nonrelatives (19). With the association of ing T, Dziewas R, Berger K, Ringelstein EB: High-normal prehypertension with microalbuminuria, it is likely that many is associated with poor cognitive perfor- individuals with prehypertension would be identified with mance. Hypertension 51: 663–668, 2008 screening. That a relative has CKD should motivate those iden- 10. Nguyen TT, Wang JJ, Wong TY: Retinal vascular changes in pre-diabetes and prehypertension: New findings and tified to change lifestyle or take medication to prevent devel- their research and clinical implications. Diabetes Care 30: oping CKD. 2708–2715, 2007 11. 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