View source for Albuminuria

{{short description|Abnormal presence of albumin in the urine}}
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{{Infobox medical condition (new)
| name          = Albuminuria
| synonym       = Proteinuria
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| specialty     = [[Nephrology]]
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| causes        = Diabetes (Type 1 & Type 2), Hypertension, Urinary tract infections, Kidney Disease, Certain Medications
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'''Albuminuria''' is a [[pathology|pathological]] condition of elevated [[serum albumin|albumin]] protein in the [[urine]] (often measured as urine albumin-to-[[creatinine]] ratio of >30 milligrams of albumin per 1 gram of creatinine per day).<ref>{{Cite web |title=Urine albumin-creatinine ratio (uACR) {{!}} National Kidney Foundation |url=https://www.kidney.org/kidney-topics/urine-albumin-creatinine-ratio-uacr |access-date=2025-03-18 |website=www.kidney.org |language=en}}</ref> It is a type of [[proteinuria]], and is the most common protein detected on urinalysis that, when elevated, is associated with kidney and cardiovascular disease (CVD). Albumin is an abundant [[blood proteins|plasma protein]] (present in blood) which is normally prevented from being lost into the urine by the sieve-like [[Glomerulus (kidney)|glomeruli]] of the nephrons. In healthy people, only trace amounts of it are present in urine, but when the filtration system of the kidney is damaged, larger amounts of albumin escape into the urine, which can be quantified and used to determine the extent of kidney injury/[[kidney disease]].<ref name="Eknoyan_2013">{{cite journal |vauthors=Stevens PE, Ahmed SB, Carrero JJ, Foster B, Francis A, Hall RK, Herrington WG, Hill G, Inker LA, Kazancıoğlu R, Lamb E, Lin P, Madero M, McIntyre N, Morrow K, Roberts G, Sabanayagam D, Schaeffner E, Shlipak M, Shroff R, Tangri N, Thanachayanont T, Ulasi I, Wong G, Yang C, Zhang L, Levin A |date=April 2024 |title=KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease |journal=Kidney International |language=English |volume=105 |issue=4S |pages=S117–S314 |doi=10.1016/j.kint.2023.10.018 |pmid=38490803|doi-access=free }}</ref>

==Signs and symptoms==
Albuminuria is often asymptomatic in low quantities but foamy [[urine]] may be present. As significant albumin is lost to the urine, swelling of the ankles, hands, belly or face may occur (see [[edema]] and [[nephrotic syndrome]]). This is because a major role of albumin in the blood is to act as an [[Osmosis|osmotic]] agent, keeping water from leaving blood vessels and leaking into the surrounding body tissues.<ref>{{cite journal | vauthors = Levitt DG, Levitt MD | title = Human serum albumin homeostasis: a new look at the roles of synthesis, catabolism, renal and gastrointestinal excretion, and the clinical value of serum albumin measurements | journal = International Journal of General Medicine | volume = 9 | pages = 229–255 | date = 2016 | pmid = 27486341 | pmc = 4956071 | doi = 10.2147/ijgm.s102819 | doi-access = free }}</ref>

==Causes==
Albuminuria is not a disease itself but a marker of kidney injury, particularly to the filtration mechanism (glomerulus), and can be caused by a number of pathological states, including:

* [[Diabetic nephropathy]]
* [[Hypertension]]
* Various [[Autoimmunity|autoimmune]] disorders
** [[Lupus nephritis]]
** [[IgA nephropathy]]
** [[Anti-neutrophil cytoplasmic antibody|ANCA-associated vasculitis]]
** [[Goodpasture syndrome|Anti-GBM disease]] (Goodpasture's syndrome)
** [[Membranous glomerulonephritis|Membranous nephropathy]]
** [[Antiphospholipid syndrome]]
** [[Alport syndrome]]
** [[Sjögren's disease|Sjogren syndrome]]
* [[Dehydration]] / low blood volume
* [[Cardiovascular disease]]
* [[Nephrotoxicity|Nephrotoxic medications]]
* [[Pyelonephritis|Infections]]
* [[Urinary tract obstruction]]

In all cases, the result is a loss of the kidney's ability to retain albumin from the urine.<ref name="Eknoyan_2013" />
==Diagnosis/Testing==
According to Kidney Disease Improving Global Outcomes (KDIGO) guidelines, albuminuria is categorized into 3 grades with increasing severity of associated kidney injury: A1, A2, and A3. This grading scale, along with [[Glomerular filtration rate|estimated glomerular filtration rate]], is used to assess risk of progression and severity of kidney disease, particularly in [[chronic kidney disease]].<ref name="Eknoyan_2013" />
{| class="wikitable"
|+ KDIGO Albuminuria Categories Based on Urine ACR
! Albuminuria Category
! ACR (mg/mmol)
! ACR (mg/g)
|-
| A1 (normal to mildly increased)
| <3
| <30
|-
| A2 (moderately increased)
| 3–30
| 30–300
|-
| A3 (severely increased)
| >30
| >300
|}
Various tests are available to measure albuminuria. [https://www.mayoclinic.org/tests-procedures/urinalysis/about/pac-20384907#:~:text=A%20dipstick%20%E2%80%94%20a%20thin%2C%20plastic%20stick,typical%20levels.%20A%20dipstick%20test%20checks%20for: Urine dipstick analysis] can provide a qualitative estimate of the amount of albumin in the urine sample. More quantitative and accurate testing include a [https://www.kidney.org/kidney-topics/urine-albumin-creatinine-ratio-uacr#:~:text=categories%20or%20ranges.-,This%20test%20only%20requires%20a%20one%2Dtime%20urine%20sample%2C%20also,check%20using%20the%20dipstick%20method. spot sample urinalysis] and a [https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/24hour-urine-collection#:~:text=What%20is%20a%2024%2Dhour,High%20blood%20pressure. 24-hour urine collection analysis].<ref>{{Cite web |title=Urine albumin-creatinine ratio (uACR) {{!}} National Kidney Foundation |url=https://www.kidney.org/kidney-topics/urine-albumin-creatinine-ratio-uacr#:~:text=categories%20or%20ranges.-,This%20test%20only%20requires%20a%20one-time%20urine%20sample,%20also,check%20using%20the%20dipstick%20method. |access-date=2025-03-19 |website=www.kidney.org |language=en}}</ref>

== Treatment ==
Because albuminuria is a sign of underlying kidney injury/disease, treatment should be aimed at the causative factor/s. Common methods of improving and preserving kidney function include medication and lifestyle modifications such as diet and exercise.<ref>{{Cite journal |last1=Ma |first1=Qirui |last2=Gao |first2=Ye |last3=Lu |first3=Jiandong |last4=Liu |first4=Xinhong |last5=Wang |first5=Ruolin |last6=Shi |first6=Yajun |last7=Liu |first7=Jingqi |last8=Su |first8=Hao |date=2022-09-26 |title=The effect of regular aerobic exercise on renal function in patients with CKD: A systematic review and meta-analysis |journal=Frontiers in Physiology |language=English |volume=13 |doi=10.3389/fphys.2022.901164 |doi-access=free |issn=1664-042X |pmc=9549134 |pmid=36225309}}</ref> Blood pressure control, especially with the use of inhibitors of the [[Renin-Angiotensin-Aldosterone system|renin-angiotensin-system]], is the most commonly used therapy to control albuminuria.<ref>{{cite journal | vauthors = Ksiazek SH, Hu L, Andò S, Pirklbauer M, Säemann MD, Ruotolo C, Zaza G, La Manna G, De Nicola L, Mayer G, Provenzano M | title = Renin-Angiotensin-Aldosterone System: From History to Practice of a Secular Topic | journal = International Journal of Molecular Sciences | volume = 25 | issue = 7 | pages = 4035 | date = April 2024 | pmid = 38612843 | pmc = 11012036 | doi = 10.3390/ijms25074035 | doi-access = free }}</ref>

== References ==
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{{Medical resources
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|  ICD10          = {{ICD10|R80}} 
|  ICD9           = {{ICD9|791.0}} 
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|  MeshID         = D000419 
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{{EB1911 poster|Albuminuria}}

{{Abnormal clinical and laboratory findings for urine}}

[[Category:Abnormal clinical and laboratory findings for urine]]