How Psoriatic Arthritis Is Diagnosed, According to a Rheumatologist
There’s no one definitive test.

Psoriatic arthritis—an inflammatory and chronic type of arthritis—affects up to 30 percent of people with psoriasis, according to the National Psoriasis Foundation (NPF). If you have psoriasis, it’s a good idea to be aware of the symptoms of psoriatic arthritis (PsA), because catching it early, if it does develop, may improve treatment outcome.
If you do notice the telltale signs of PsA, such as pain and stiffness in the joints, what’s the next step? Unfortunately, there’s no single test that can diagnose PsA with a yes-or-no answer. Instead, a combination of different exams can help doctors form a PsA diagnosis, according to Leah Anon, MD, rheumatologist at Harlem Health Center and Queens Health Center in New York City.
Here are the factors doctors consider before diagnosing with PsA:
-
The patient’s symptoms, including when they started, where the stiffness is occurring, and how much it impacts daily life
-
Personal history of psoriasis
-
Family history of psoriasis
-
A physical exam
-
An X-ray or MRI to check for inflammation or damage to the joints
-
And blood tests to rule out other conditions.
Other Conditions to Rule Out
Many health conditions can cause joint pain, and psoriatic arthritis can mimic some of them. In particular, doctors need to rule out other types of arthritis like rheumatoid arthritis and gout, according to NPF. Many blood tests used to diagnose PsA are actually meant to rule out these similar conditions.
A blood test that evaluates the “rheumatoid factor” checks for a certain antibody that is typically present in someone with rheumatoid arthritis, but not PsA. (It’s possible, but rare, to have both rheumatoid arthritis and PsA.)
Since PsA usually affects the distal joints close to the nails in the fingers and toes, pain in the toe could be mistaken for gout. To rule out gout, doctors test joint fluid for elevated levels of serum uric acid—a possible sign of gout.
Although symptoms of the different conditions are similar, they have some key differences:
-
Joint pain caused by gout will usually strike a single joint—often the big toe—very suddenly. Gout causes intense pain.
-
If there is no swelling in the joints, it is likely osteoarthritis instead of PsA. Another sign of osteoarthritis is pain after activities, whereas PsA causes stiffness and pain in the mornings.
-
If joint pain is symmetrical and affects the same joints on both sides of the body, it is likely rheumatoid arthritis. PsA joint pain is usually asymmetrical.
-
PsA also has unique symptoms, such as skin lesions, nail changes, and dactylitis, which is when fingers and toes become swollen and take on a sausage-like appearance.
If you think you have PsA—or any of the related conditions—it’s best to visit your doctor for a professional diagnosis. The sooner you begin treatment for psoriatic arthritis, the more likely you are to avoid permanent joint damage and improve your quality of life.
Dr. Alon is a board-certified rheumatologist in New York City.
1
00:00:00,104 --> 00:00:02,732
[MUSIC]
2
00:00:02,732 --> 00:00:05,123
When it comes to diagnosing
psoriatic arthritis,
3
00:00:05,123 --> 00:00:08,858
it's important to know there's not one
single test that instantly tells you.
4
00:00:08,858 --> 00:00:13,676
[MUSIC]
5
00:00:13,676 --> 00:00:16,952
Because psoriatic arthritis can
look similar to other conditions,
6
00:00:16,952 --> 00:00:19,558
we will often do certain tests
to try to rule those out.
7
00:00:19,558 --> 00:00:22,022
We ask patients to tell
us about their symptoms,
8
00:00:22,022 --> 00:00:24,906
how they started where in your
body you're having pain or
9
00:00:24,906 --> 00:00:28,290
stiffness, and how your symptoms
effect your daily activities.
10
00:00:28,290 --> 00:00:32,026
We will do a physical exam, and might
order x-rays to look for inflammation and
11
00:00:32,026 --> 00:00:33,105
damage in the joints.
12
00:00:33,105 --> 00:00:35,724
We can test joint fluid
to try to rule our gout.
13
00:00:35,724 --> 00:00:39,552
If a single joint becomes swollen and
extremely painful almost overnight,
14
00:00:39,552 --> 00:00:42,077
it's probably gout,
not psoriatic arthritis.
15
00:00:42,077 --> 00:00:46,032
We'll do a blood test to check for
something called rheumatoid factor and
16
00:00:46,032 --> 00:00:46,744
anti-CCP.
17
00:00:46,744 --> 00:00:49,192
They're present in people
with rheumatoid arthritis,
18
00:00:49,192 --> 00:00:51,081
but less commonly in psoriatic arthritis.
19
00:00:51,081 --> 00:00:54,479
Certain symptoms can also help
us rule out other conditions.
20
00:00:54,479 --> 00:00:56,502
If you have little or no joint swelling,
21
00:00:56,502 --> 00:01:00,400
there's a good chance you have
osteoarthritis, not psoriatic arthritis.
22
00:01:00,400 --> 00:01:04,350
People with psoriatic arthritis tend
to wake up feeling stiff or in pain.
23
00:01:04,350 --> 00:01:05,668
Doctors can also test for
24
00:01:05,668 --> 00:01:09,445
a gene that can be related to psoriatic
arthritis involving the spine.
25
00:01:09,445 --> 00:01:12,940
There are some symptoms that tend to
be unique to psoriatic arthritis.
26
00:01:12,940 --> 00:01:17,400
Skin lesions, nail problems and
specific patterns of inflammation
27
00:01:17,400 --> 00:01:20,250
usually let us differentiate
it from other conditions.
28
00:01:20,250 --> 00:01:22,550
If your fingers or
toes are completely swollen,
29
00:01:22,550 --> 00:01:24,900
that's another likely sign
it's psoriatic arthritis.
30
00:01:24,900 --> 00:01:28,460
This is called dactylitis or
sausage fingers.
31
00:01:28,460 --> 00:01:31,352
If you are at all concerned
that your skin issues, pain,
32
00:01:31,352 --> 00:01:35,651
or other symptoms could potentially be
psoriatic arthritis, please see a doctor.
33
00:01:35,651 --> 00:01:38,501
Starting treatment early can
help prevent joint damage, and
34
00:01:38,501 --> 00:01:40,541
improve your symptoms and quality of life.
35
00:01:40,541 --> 00:01:45,172
[MUSIC]
About psoriatic arthritis. Portland, OR: National Psoriasis Foundation. (Accessed on April 15, 2021 at https://www.psoriasis.org/about-psoriatic-arthritis#symptoms.)
Gout. Portland, OR: National Psoriasis Foundation. (Accessed on April 15, 2021 at https://www.arthritis.org/about-arthritis/types/gout/.)
Psoriatic arthritis. Atlanta, GA: American College of Rheumatology. (Accessed on April 15, 2021 at https://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Psoriatic-Arthritis.)
Psoriatic arthritis. Portland, OR: National Psoriasis Foundation. (Accessed on April 15, 2021 at https://www.psoriasis.org/psoriatic-arthritis.)