TOW #46: Hematuria

Until recommendations changed in 2008, pediatricians routinely performed urinalysis screening in otherwise healthy children. This is no longer recommended, so we may not encounter microscopic hematuria quite as often. However, knowledge of how we approach hematuria in the outpatient setting is helpful to review given the possibility of medical complications.

Materials for this week:

Take-home points for this week on hematuria (for this,focused on the heme part, but case also reviews the protein part):

  1. Definition of hematuria: presence of 5 or more RBCs per high-power (40) field in 3 consecutive fresh, centrifuged specimens obtained over several weeks. There is microscopic (visible only on testing) or macroscopic (gross) hematuria (visible to the eye). Beware of false hematuria from drugs, foods (e.g.,beets, blackberries), toxins (e.g., lead), and urate crystals in newborns.
  2. Epidemiology: population studies in Finland and Texas have shown a prevalence of 3-6% of asymptomatic microscopic hematuria in school-age children in a single urine sample. With repeat screenings, prevalence declines to 0.5% to 1%. There are no differences by race/ethnicity. Until 2008, the AAP recommended urine screening routinely at age 5 and during adolescence, but this was ended due to low rates of disease and high false positives.
  3. Types of hematuria: Diagnostic evaluation depends on the category: gross hematuria, symptomatic microscopic hematuria, asymptomatic microscopic hematuria with proteinuria, or isolated asymptomatic microscopic hematuria. Evaluating RBC morphology helps distinguish glomerular and extraglomerular sources. Glomerular bleeding is typically “cola-colored,” with RBC casts and distorted RBC morphology.
  4. Hematuria type determines need for work-up: see the above algorithm. We have to distinguish between asymptomatic microscopic hematuria which is usually benign and requires conservative management, and hematuria with accompanying proteinuria, edema, hypertension, or other symptoms which suggests underlying renal disease. Underlying causes of gross hematuria are identified in 56% of cases including UTI, trauma, kidney stones, hypercalciuria, coagulopathy and kidney disease.
  5. Initial next steps: Repeat the urine test with microscopy, identify other symptoms, and review family history of renal disease. For persistent proteinuria, a morning and evening urine will be needed to identify orthostatic proteinuria, which accounts for 60% of asymptomatic proteinuria cases. If the patient has any markers of serious glomerular pathology, a basic metabolic panel, CBC, C3, C4, albumin, ANA, anti-streptolysin (ASO) and anti-DNAse B titers, and streptozyme would be recommended.

TOW #23: Hypertension

This year, updated guidelines for hypertension were released by the AAP with the lead author our own nephrologist, Dr. Joseph Flynn. Next week we will focus on reviewing this topic and familiarizing ourselves with the updates. This is a dense one, so try to at least review some of the key tables and summarized recommendations in the practice guidelines.

Materials for this week:

Take-home points:

  1. How do we define “hypertension” in the pediatric patient? What’s the difference between elevated BP (previously “prehypertension”), stage 1 hypertension, and stage 2 hypertension? There is no known cut-off for elevated BP in childhood that affects cardiovascular (CV) outcomes, so the definition of HTN in children and adolescents is based on the normative distribution of BP in healthy children (excluding those with overweight/obesity) based age, sex and height. Height has been incorporated since 1996 since it affects BP measurement. Persistently elevated BP (formerly termed “prehypertension,”) is defined as BP values from the 90th to 94th percentiles or between 120/80 and 130/80 mmHg in adolescents. Stage 1 HTN is defined as auscultatory-confirmed BP readings at 3 different visits ≥95th percentile (or <95th percentile +12 mmHg) or 130/80 to 139/89 mmHg (whichever is lower). Stage 2 HTN is ≥95th percentile + 12 mmHg, or ≥140/90 mmHg (whichever is lower). Thankfully, for adolescents it’s easier to remember as Stage 1 and 2 are aligned with adults, so it’s 130/80 to 139/89 mmHg or ≥140/90 mmHg, respectively.
  2. What’s the prevalence of clinical HTN in children and adolescents? Prevalence of HTN is ∼3.5%.‍ Persistently elevated BP (formerly termed “prehypertension”) is also ∼2.2% to 3.5%. The rates are higher among children and adolescents who have overweight and obesity, so these children’s data were removed from the new tables in the updated guidelines (cut-points are therefore lower than they used to be).‍
  3. Which children and adolescents need regular blood pressure monitoring and how should BP be obtained? We should be checking BP annually at all well visits for ages 3+. We should do it at all visits for children <3 who have an underlying risk factor (e.g., prematurity <32 weeks, congenital heart disease, renal disease, UTIs, transplant, etc). The guidelines state that we can use automated oscillometric devices for BP measurement, as long as they are validated for pediatrics. If elevated BP is suspected, we should confirm with auscultation. If the initial BP at an office visit is elevated, we should obtain 2 additional BP measurements at the same visit and average them, then use the averaged auscultatory BP measurement to determine the patient’s BP category (throwing out the automated one). If HTN is suspected/diagnosed, we should do ambulatory blood pressure monitoring to rule out white coat hypertension and determine persistence/severity of HTN.
  4. What work-up do we need to do to evaluate for secondary causes, comorbidities, and end-organ damage in the pediatric hypertensive patient? Use the history and PE to identify possible underlying causes of HTN, such as heart disease, kidney disease, renovascular disease, endocrine-related, drug-induced, and sleep apnea-associated HTN. Recommended work-up for all patients includes: BP of both upper extremities and at least 1 leg BP, Urinalysis, Chemistry panel (including electrolytes, BUN/Cr), Lipid profile (fasting or nonfasting), Renal ultrasonography in those <6 y of age or those with abnormal urinalysis or renal function. Children and adolescents ≥6 y of age do not require an extensive work-up for secondary causes of HTN if they have a positive family history of HTN, are overweight or obese, and/or do not have history or physical examination findings suggestive of a secondary cause of HTN. If starting pharmacologic treatment for HTN, it is recommended that echocardiography be done to assess for cardiac organ damage.
  5. How do we treat hypertension in children? The treatment goal is reduction in SBP and DBP to <90th percentile and <130/80 mmHg in adolescents ≥ 13yo. At the time of diagnosis of elevated BP or HTN, we should provide advice on the DASH diet (which has evidence of benefit for youth) and recommend moderate to vigorous physical activity at least 3 to 5 d per week (30–60 min per session) (evidence level C). We should also consider subspecialty referral. If lifestyle modifications are not successful, and especially if there is LV hypertrophy on echo, symptomatic HTN, or stage 2 HTN, clinicians should initiate pharmacologic treatment with an ACE inhibitor, ARB, long-acting calcium channel blocker, or thiazide diuretic.