Clinical assessment method
Clinical examination of subcutaneous adipose tissue is performed simultaneously with the inspection of the skin. The physician evaluates two key parameters: the degree of fat mass deposition and the presence of occult or overt edema.
The degree of development of the fat layer is determined by palpation. To do this, the physician gently grasps a fold of skin along with the subcutaneous tissue using the thumb and index finger. To obtain a reliable picture, the grasp must be performed in four anatomical zones:
- On the abdomen (in the umbilical region).
- In the subscapular spaces.
- On the inner surfaces of the arms.
- On the inner surfaces of the thighs.
Interpretation of results: if the skin is easily gathered into a fold, this indicates malnutrition. In significant obesity, forming a fold is extremely difficult or physically impossible.
Excessive fat deposition
Obesity is classified depending on the distribution pattern of adipose tissue. In typical obesity, fat is deposited relatively evenly, although an abdominal distribution type often predominates.
Dysplastic (abnormal) obesity is prominently manifested in Cushing's syndrome or disease. This pathology is caused by an excess of glucocorticoids (due to an ACTH-producing pituitary tumor, adrenal tumor, or exogenous hormone intake).
The "cushingoide" phenotype includes:
- Moon face (specific rounding due to fat on the cheeks).
- "Buffalo hump" (pronounced fat pad on the back of the neck).
- Marked body disproportion: massive fat deposition on the upper body with abnormally thin extremities.
Due to overstretching, areas of atrophy—striae—occur on the skin. In hypercortisolism, they have a characteristic purplish-bluish color. For differential diagnosis, it is important to remember that whitish striae occur for other reasons: after childbirth, with massive ascites, or prolonged nutritional obesity.
Weight loss syndromes
Inadequate development of SAT is called lipodystrophy. It can be local (e.g., localized fat loss in insulin injection sites in diabetes mellitus) and generalized, leading to general wasting.
The extreme form of wasting is cachexia. This condition is accompanied by severe emaciation, pronounced physical weakness, and suppression of all physiological functions. At the neuropsychiatric level, asthenic syndrome initially develops, which is eventually replaced by profound apathy.
Pathogenetic mechanisms and causes of weight loss:
- Nutritional factors: nutritional deficiency in the elderly, alcoholism, depression, dementia, or anorexia nervosa.
- Gastrointestinal pathologies: malabsorption syndrome, severe diarrhea, parasitic infestations.
- Endocrine disorders: decompensated diabetes mellitus, thyrotoxicosis.
- Oncology: malignant tumors—the most common cause of cancer cachexia.
- Chronic inflammation: tuberculosis, rheumatoid arthritis, COPD.
- Organ failure: terminal stages of heart or pulmonary failure.
Important: Rapid weight loss can be iatrogenic. For example, active diuretic therapy leads to fluid loss and the resolution of edema, rather than a decrease in tissue volume.
Focal pathological lesions
Palpation of the subcutaneous fat layer may reveal local nodes and indurations that require differential diagnosis. The main types of lesions:
- Lipomas: benign accumulations of fat. To the touch, they are completely painless and have clear borders (encapsulated areas).
- Panniculitis (aseptic or purulent): inflammatory lesions of SAT. Unlike lipomas, they are sharply painful upon palpation, and the skin over them is always hyperemic.
Briefly: answers to topical questions
What is the normal thickness of the skinfold in the umbilical region?
Normally, the thickness of the skinfold on the abdomen (at the umbilical level) is about 1–2 cm. At the same time, the subcutaneous adipose tissue is moderately developed, distributed evenly, and painless. If the fold thickness is less than 0.5 cm, it indicates emaciation, and if it exceeds 2–2.5 cm, it indicates excessive development of adipose tissue.
What are the degrees of obesity depending on the body mass index (BMI)?
Depending on BMI, the following degrees of obesity are distinguished:
- Grade I obesity — BMI from 30.0 to 34.9 kg/m².
- Grade II obesity — BMI from 35.0 to 39.9 kg/m².
- Grade III obesity — BMI $\ge$ 40 kg/m².
Also, lower threshold values (27.5, 32.5, and 37.5 kg/m² for grades 1, 2, and 3, respectively) can be used to assess the risk of complications.
Class and exam questions
What do purple and white striae on the skin indicate?
Purplish-bluish striae indicate hypercortisolism (Cushing's syndrome). Whitish striae appear due to banal skin overstretching after pregnancy, with massive ascites, or dietary obesity.
How does cachexia differ from simple weight loss?
Cachexia is an extreme degree of generalized wasting characterized by the loss of not only subcutaneous but also visceral fat, along with muscle atrophy. It is accompanied by severe weakness, suppression of organ functions, and a transition from asthenia to apathy.
How to distinguish a lipoma from panniculitis by palpation?
A lipoma is palpated as a clearly demarcated and completely painless nodule. Panniculitis is always accompanied by marked tenderness upon touch and erythema of the skin over the inflammation site.
What else to study on this topic
- Anthropometric methods for assessing obesity phenotype
- Visceral fat and its metabolic activity
- Pathogenesis of malabsorption syndrome
- Mechanisms of aseptic panniculitis development
- Differential diagnosis of edematous syndrome and weight gain
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