{"id":61692,"date":"2021-04-21T13:16:22","date_gmt":"2021-04-21T11:16:22","guid":{"rendered":"https:\/\/wpcalc.com\/?p=61692"},"modified":"2026-10-01T13:27:02","modified_gmt":"2026-10-01T10:27:02","slug":"dialysis-dose","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/medical\/dialysis-dose\/","title":{"rendered":"Dialysis Dose (Kt\/V) Calculator"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Estimate Dialysis Dose Kt\/V<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"61692\" data-favorite-title=\"Dialysis Dose (Kt\/V)\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/medical\/dialysis-dose\/\" data-favorite-excerpt=\"Estimate hemodialysis adequacy with the second-generation Daugirdas Kt\/V formula. Enter post-dialysis weight, ultrafiltration volume, and pre- and post-dialysis BUN to calculate the delivered dialysis dose.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-pharmacology\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/medical\/dialysis-dose\/\" method=\"POST\" class=\"calculator\" id=\"calculator-61692\" data-post=\"61692\"><fieldset class=\"fieldset-input is-1\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Post-dialysis weight<\/label><input type=\"number\" name=\"postdialysis_weight\" id=\"field-1\" aria-describedby=\"calc-unit-1\" placeholder=\"e.g. 70\" step=\"any\" value=\"70\"\/><div class=\"unit\" id=\"calc-unit-1\">kg<\/div><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">Ultrafiltration volume<\/label><input type=\"number\" name=\"ultrafiltration_volume\" id=\"field-2\" aria-describedby=\"calc-unit-2\" placeholder=\"e.g. 2.0\" step=\"any\" value=\"2\"\/><div class=\"unit\" id=\"calc-unit-2\">L<\/div><\/div><div class=\"field\" id=\"input-3\"><label for=\"field-3\">Predialysis BUN<\/label><div class=\"field-group\"><input type=\"number\" name=\"predialysis_bun\" id=\"field-3\" placeholder=\"e.g. 60\" step=\"any\" value=\"60\"\/><div class=\"grid grid-cols-1\"><select id=\"field-4\" name=\"unit\" aria-label=\"Unit\"><option value=\"1\" selected>mg\/dL<\/option><option value=\"0.375\">mmol\/L<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><\/div><div class=\"field\" id=\"input-4\"><label for=\"field-5\">Postdialysis BUN<\/label><div class=\"field-group\"><input type=\"number\" name=\"postdialysis_bun\" id=\"field-5\" placeholder=\"e.g. 20\" step=\"any\" value=\"20\"\/><div class=\"grid grid-cols-1\"><select id=\"field-6\" name=\"unit\" aria-label=\"Unit\"><option value=\"1\" selected>mg\/dL<\/option><option value=\"0.375\">mmol\/L<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"61692\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Your Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Kt\/V<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"61692\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">1<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">1<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Kt\/V Formula for Hemodialysis<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[ Kt\/V = -\\ln(R - 0.03) + \\left(4 - 3.5 \\cdot R\\right) \\cdot \\left(\\frac{UF}{W}\\right), \\quad R = \\frac{\\text{PostBUN}}{\\text{PreBUN}} \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(R\\) \u2014 ratio of post-dialysis BUN to pre-dialysis BUN<\/li>\n<li>\\(UF\\) \u2014 ultrafiltration volume removed during the session (L)<\/li>\n<li>\\(W\\) \u2014 post-dialysis body weight (kg)<\/li>\n<li>\\(Kt\/V\\) \u2014 fractional urea clearance: dialyzer clearance \\(K\\) multiplied by treatment time \\(t\\), divided by the urea distribution volume \\(V\\)<\/li>\n<\/ul>\n<p>This is the second-generation Daugirdas formula, the standard bedside method for estimating the single-pool Kt\/V of a hemodialysis session. The logarithmic term captures urea removal, while the second term corrects for the additional clearance achieved through ultrafiltration (convective removal of urea with the removed water).<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Kt\/V \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a patient finishes dialysis at a post-dialysis weight of 70 kg after 2 L of ultrafiltration. The predialysis BUN is 60 mg\/dL and the postdialysis BUN is 20 mg\/dL.<\/p>\n<p>\\[ R = \\frac{20}{60} = 0.333 \\]<\/p>\n<p>\\[ Kt\/V = -\\ln(0.333 - 0.03) + (4 - 3.5 \\cdot 0.333) \\cdot \\frac{2}{70} \\]<\/p>\n<p>\\[ Kt\/V = -\\ln(0.303) + 2.833 \\cdot 0.0286 = 1.193 + 0.081 \\]<\/p>\n<p><strong>Result:<\/strong> Kt\/V \u2248 1.274, which exceeds the minimum adequacy target of 1.2 for a thrice-weekly hemodialysis session.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Calculator<\/h2>\n<ol>\n<li>Enter the <strong>Post-dialysis weight<\/strong> in kilograms \u2014 this is the patient's estimated dry weight at the end of the session.<\/li>\n<li>Enter the <strong>Ultrafiltration volume<\/strong> in liters \u2014 the total fluid removed during the treatment.<\/li>\n<li>Enter the <strong>Predialysis BUN<\/strong> value drawn before the session starts, and select the unit (mg\/dL or mmol\/L) from the dropdown next to the field.<\/li>\n<li>Enter the <strong>Postdialysis BUN<\/strong> value drawn at the end of the session, again selecting the matching unit. The calculator converts mmol\/L values to mg\/dL automatically.<\/li>\n<li>Read the <strong>Kt\/V<\/strong> result, rounded to three decimal places, below the inputs.<\/li>\n<\/ol>\n<p>Note: the postdialysis BUN must be lower than the predialysis BUN; otherwise the calculator reports an error, since a rising or unchanged BUN cannot yield a meaningful dialysis dose.<\/p>\n<h2>What Is Kt\/V and Why Does It Matter?<\/h2>\n<p>Kt\/V is a dimensionless number that quantifies how effectively a dialysis session clears urea from the body. It is the product of dialyzer urea clearance \\(K\\) (mL\/min) and treatment time \\(t\\) (minutes), divided by the patient's urea distribution volume \\(V\\) (approximately equal to total body water). A Kt\/V of 1.0 means the equivalent of the entire urea distribution volume was cleared once during the session \u2014 in practice, slightly less removal is achieved because urea rebounds between compartments after treatment ends.<\/p>\n<p>Because it is normalized to body size, Kt\/V allows meaningful comparison of dialysis dose between patients of different weights and between different treatment prescriptions (shorter vs. longer sessions, smaller vs. larger dialyzers). Large clinical trials such as HEMO and NCDS established Kt\/V as the primary measure of hemodialysis adequacy, and guidelines from the National Kidney Foundation (KDOQI) recommend a minimum single-pool Kt\/V of 1.2 per session for patients on thrice-weekly hemodialysis, with a target of about 1.4 to provide a safety margin.<\/p>\n<p>Interpreting the result is straightforward: values below 1.2 suggest underdialysis and are associated with higher mortality, malnutrition, and persistent uremic symptoms; values between roughly 1.2 and 1.4 are considered adequate; and very high values achieved by excessively long or fast treatments may cause hypotension and disequilibrium without adding clinical benefit. A single Kt\/V value should always be interpreted alongside the patient's symptoms, nutrition, and trend over multiple sessions rather than in isolation.<\/p>\n<h2>Assumptions, Limitations, and Practical Tips<\/h2>\n<ul>\n<li><strong>Post-dialysis sampling matters.<\/strong> The formula assumes the postdialysis BUN is drawn with the slow-flow or stop-pump technique immediately at the end of treatment. Sampling too late (after urea rebound) or too early overestimates or underestimates the true dose.<\/li>\n<li><strong>Single-pool model.<\/strong> The Daugirdas II formula gives single-pool Kt\/V (spKt\/V). Equilibrated Kt\/V (eKt\/V), which accounts for post-treatment urea rebound, is typically 0.15\u20130.20 lower.<\/li>\n<li><strong>Steady-state assumptions.<\/strong> The calculation assumes a stable patient without major residual kidney function contributions, large urea generation shifts, or missed sessions. In peritoneal dialysis, weekly Kt\/V is used instead, and this formula does not apply.<\/li>\n<li><strong>Residual renal function.<\/strong> Patients with substantial remaining native kidney clearance may achieve good outcomes at a lower delivered dialysis Kt\/V, because total urea clearance includes renal clearance.<\/li>\n<li><strong>Clinical use only as an estimate.<\/strong> This tool supports quick assessment and teaching; formal adequacy assessment should use validated laboratory measurement protocols and clinical judgment.<\/li>\n<\/ul>\n<p>For related bedside calculations, see the <a href=\"https:\/\/wpcalc.com\/en\/medical\/clinical-dehydration-scale\/\">Clinical Dehydration Scale<\/a> for assessing fluid status, the <a href=\"https:\/\/wpcalc.com\/en\/medical\/half-life-time-medicine\/\">Half-Life Time calculator<\/a> for understanding first-order elimination kinetics like urea clearance, and the <a href=\"https:\/\/wpcalc.com\/en\/medical\/mean-arterial-pressure\/\">Mean Arterial Pressure calculator<\/a> for hemodynamic monitoring during treatment.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Estimate hemodialysis adequacy with the second-generation Daugirdas Kt\/V formula. Enter post-dialysis weight, ultrafiltration volume, and pre- and post-dialysis BUN to calculate the delivered dialysis dose.<\/p>\n","protected":false},"author":70,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[8],"tags":[32],"class_list":["post-61692","post","type-post","status-publish","format-standard","hentry","category-medical","tag-pharmacology"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/61692","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/70"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=61692"}],"version-history":[{"count":4,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/61692\/revisions"}],"predecessor-version":[{"id":66318,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/61692\/revisions\/66318"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=61692"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=61692"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=61692"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}