Hypothyroidism: This condition is a common cause of both joint swelling (due to fluid accumulation) and constipation (as a result of decreased gut motility). The symptoms can be subtle and gradual, making it a likely consideration in patients presenting with these complaints.

Rheumatoid Arthritis (RA): While RA primarily causes joint symptoms, some patients may experience gastrointestinal symptoms, including constipation, either as a side effect of medication or due to the disease itself. The joint swelling in RA is typically symmetric and involves the hands and feet.
Osteoarthritis (OA): OA can cause joint swelling, especially in the context of an acute flare, and constipation might be related to decreased mobility or as a side effect of pain medications. However, OA is less likely to cause significant systemic symptoms compared to RA.
Fibromyalgia: This condition is characterized by widespread musculoskeletal pain, fatigue, and sleep issues. Some patients with fibromyalgia may experience gastrointestinal symptoms, including constipation. Joint swelling is not a primary feature, but pain and stiffness can mimic swelling.

Hyperparathyroidism: This condition can lead to hypercalcemia, which may cause constipation. Joint symptoms can arise from bone resorption and calcium deposition in joints. Although less common, missing this diagnosis can lead to significant morbidity.
Amyloidosis: A rare condition where abnormal proteins (amyloid) accumulate in various tissues, including joints and the gastrointestinal tract, leading to symptoms like joint swelling and constipation. It's crucial to consider amyloidosis due to its potential for severe outcomes if left untreated.
Sarcoidosis: This inflammatory disease can affect multiple systems, including joints (causing swelling) and the gastrointestinal system (leading to constipation among other symptoms). It's essential to recognize sarcoidosis early due to its potential for serious complications.

Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. Some types can lead to joint hypermobility and gastrointestinal issues, including constipation. However, the combination of joint swelling and constipation as primary symptoms is less common.
Sjögren's Syndrome: An autoimmune disorder that primarily affects the glands that produce tears and saliva but can also cause joint pain and swelling. Gastrointestinal symptoms, including constipation, can occur. It's a rare consideration for these specific symptoms but should be kept in mind, especially in patients with other autoimmune diseases.